diff --git a/.conda/README.md b/.conda/README.md
index 67d38c9738..902237be9f 100644
--- a/.conda/README.md
+++ b/.conda/README.md
@@ -45,8 +45,17 @@ _Cela fonctionne aussi sous macOS et Linux, à condition d'adapter les chemins._
 
 Docker peut être utilisé pour valider le bon fonctionnement
 
+Pour tester le build :
 ```
-docker run -i -t continuumio/anaconda3 /bin/bash
+docker run --volume $PWD:/openfisca -i -t continuumio/anaconda3 /bin/bash
+cd /openfisca
+conda build -c openfisca -c conda-forge .conda
+```
+
+Pour tester l'installation :
+```
+docker run --volume $PWD:/openfisca -i -t continuumio/anaconda3 /bin/bash
+cd /openfisca
 conda install -c openfisca -c conda-forge openfisca-france-dev
 openfisca test --country-package openfisca_france tests
 ```
\ No newline at end of file
diff --git a/.conda/meta.yaml b/.conda/meta.yaml
index 7dc68cb7a5..f8714a8427 100644
--- a/.conda/meta.yaml
+++ b/.conda/meta.yaml
@@ -1,11 +1,11 @@
 ###############################################################################
-## Fichier de description du package pour Anaconda.org
-## Attention, les chaines PYPI_VERSION, PYPI_URL et PYPI_SHA256 sont remplacées
-## par la CI, il faut les conserver.
+## File for Anaconda.org
+## It use Jinja2 templating code to retreive information from setup.py
 ###############################################################################
 
 {% set name = "OpenFisca-France" %}
-{% set version = "PYPI_VERSION" %}
+{% set data = load_setup_py_data() %}
+{% set version = data.get('version') %}
 
 package:
   name: {{ name|lower }}
@@ -24,8 +24,11 @@ requirements:
     - python
     - pip
   run:
-    - python >=3.6,<4.0
-    - OpenFisca-Core >=35.8.0,<36.0
+    {% for req in data.get('install_requires', []) %}
+    - {{ req }}
+    {% endfor %}
+    # - python >=3.9,<4.0
+    # - OpenFisca-Core >=40,<41
 
 
 test:
@@ -46,7 +49,7 @@ outputs:
       host:
         - python
       run:
-        - scipy >=0.17
+        - scipy >=1.10.1,<2.0
         - {{ pin_subpackage('openfisca-france', exact=True) }}
 
   - name: openfisca-france-dev
@@ -56,12 +59,10 @@ outputs:
       host:
         - python
       run:
-        - autopep8 ==1.5.7
-        - flake8 >=3.8.0,<3.10.0
-        - flake8-print
-        - pytest >=5.0.0, <7.0.0
-        - requests >=2.8
-        - yamllint >=1.11.1,<1.27
+        - python >=3.9,<4.0
+        {% for req in data.get('dev_requirements', []) %}
+        - {{ req }}
+        {% endfor %}
         - {{ pin_subpackage('openfisca-france-scipy', exact=True) }}
 
 about:
diff --git a/.github/test-api.sh b/.github/test-api.sh
index c8d8f9df46..a408e042e4 100755
--- a/.github/test-api.sh
+++ b/.github/test-api.sh
@@ -3,7 +3,7 @@
 PORT=5000
 ENDPOINT=spec
 
-openfisca serve --country-package openfisca_france --port $PORT &
+openfisca serve --country-package openfisca_france --port $PORT --workers 1 &
 server_pid=$!
 
 curl --retry-connrefused --retry 10 --retry-delay 5 --fail http://127.0.0.1:$PORT/$ENDPOINT | python -m json.tool > /dev/null
diff --git a/.github/workflows/workflow.yml b/.github/workflows/workflow.yml
index 5d968875f2..e18a47303a 100644
--- a/.github/workflows/workflow.yml
+++ b/.github/workflows/workflow.yml
@@ -12,7 +12,7 @@ jobs:
       fail-fast: true
       matrix:
         os: ["ubuntu-20.04"]  # On peut ajouter "macos-latest" si besoin
-        python-version: ["3.7.9", "3.8.9", "3.9.9"]
+        python-version: ["3.9.9", "3.10.6"]
     steps:
       - name: Checkout
         uses: actions/checkout@v3
@@ -48,7 +48,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: 3.7.9
+          python-version: 3.9.9
       - name: Cache build
         id: restore-build
         uses: actions/cache@v3
@@ -68,7 +68,7 @@ jobs:
       fail-fast: true
       matrix:
         os: [ "ubuntu-20.04" ]  # On peut ajouter "macos-latest" si besoin
-        python-version: ["3.7.9", "3.8.9", "3.9.9"]
+        python-version: ["3.9.9", "3.10.6"]
     steps:
       - uses: actions/checkout@v3
       - name: Set up Python
@@ -92,7 +92,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: 3.7.9
+          python-version: 3.9.9
       - name: Test max path length
         run: make check-path-length
 
@@ -112,7 +112,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: 3.7.9
+          python-version: 3.9.9
       - name: Cache build
         id: restore-build
         uses: actions/cache@v3
@@ -138,7 +138,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: 3.7.9
+          python-version: 3.9.9
       - name: Cache build
         id: restore-build
         uses: actions/cache@v3
@@ -158,7 +158,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: 3.7.9
+          python-version: 3.9.9
       - name: Check version number has been properly updated
         run: "${GITHUB_WORKSPACE}/.github/is-version-number-acceptable.sh"
 
@@ -178,7 +178,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: 3.7.9
+          python-version: 3.9.9
       - id: stop-early
         run: if "${GITHUB_WORKSPACE}/.github/has-functional-changes.sh" ; then echo "::set-output name=status::success" ; fi
 
@@ -196,7 +196,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: 3.7.9
+          python-version: 3.9.9
       - name: Cache build
         id: restore-build
         uses: actions/cache@v3
@@ -223,9 +223,9 @@ jobs:
       - uses: conda-incubator/setup-miniconda@v2
         with:
           auto-update-conda: true
-          python-version: "3.7.9"
+          python-version: "3.9.9"
           # Add conda-forge for OpenFisca-Core
-          channels: conda-forge
+          channels: openfisca,conda-forge
           activate-environment: true
       - uses: actions/checkout@v3
       - name: Update meta.yaml
@@ -239,7 +239,7 @@ jobs:
           conda install conda-build anaconda-client
           conda info
       - name: Build Conda package
-        run: conda build --croot /tmp/conda .conda
+        run: conda build -c openfisca -c conda-forge --croot /tmp/conda .conda
       - name: Upload Conda build
         uses: actions/upload-artifact@v3
         with:
@@ -256,7 +256,7 @@ jobs:
           auto-update-conda: true
           python-version: "3.9.9"
           # Add conda-forge for OpenFisca-Core
-          channels: conda-forge
+          channels: openfisca,conda-forge
           activate-environment: true
       - uses: actions/checkout@v3
       - name: Test max path length
@@ -284,7 +284,7 @@ jobs:
       - uses: conda-incubator/setup-miniconda@v2
         with:
           auto-update-conda: true
-          python-version: "3.7.9"
+          python-version: "3.9.9"
           # Add conda-forge for OpenFisca-Core
           channels: conda-forge
           activate-environment: true
diff --git a/.gitpod.Dockerfile b/.gitpod.Dockerfile
index 36481607f7..8ff1ca0598 100644
--- a/.gitpod.Dockerfile
+++ b/.gitpod.Dockerfile
@@ -1,4 +1,4 @@
-FROM python:3.7
+FROM python:3.9
 
 USER gitpod
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4fb80d91e7..6ff3672465 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,17 @@
 # Changelog
 
-### 148.0.0 [#2105](https://github.com/openfisca/openfisca-france/pull/2105)
+# 149.0.0 [#2065](https://github.com/openfisca/openfisca-france/pull/2065)
+
+* Amélioration technique.
+* Périodes concernées : toutes.
+* Zones impactées : toutes.
+* Détails :
+  - Met à jour toutes les dépendances afin d'utiliser leurs dernières versions :
+    * Migre la version minimal de Python de `3.7` à `3.9`
+    * Met à jour openfisca-core de la version `35` à la version `40`
+    * En particulier, migre la syntaxe des périodes introduite par [openfisca-core v37.0.0](https://github.com/openfisca/openfisca-core/blob/master/CHANGELOG.md#3700-1142). Les appels à la méthode `period()` sont remplacés par des instanciations de la classe `Period`.
+
+# 148.0.0 [#2105](https://github.com/openfisca/openfisca-france/pull/2105)
 
 * Amélioration technique.
 * Périodes concernées : Toutes.
@@ -34,6 +45,7 @@
   - Nettoyage et harmonisation avec les barèmes IPP
 
 ## 147.2.1 [#2097](https://github.com/openfisca/openfisca-france/pull/2097)
+
 * Évolution du système socio-fiscal.
 * Périodes concernées : à partir du 01/01/2023.
 * Zones impactées :
@@ -773,6 +785,7 @@
   - `exo_maire_autres`
   - `foncier_deduc`
   - `deduc_invest_locatif`
+
 # 134.0.0 [#1958](https://github.com/openfisca/openfisca-france/pull/1958)
 
 * Évolution du système socio-fiscal. | Amélioration technique.
diff --git a/README.md b/README.md
index d13ef06928..44b5e380a8 100644
--- a/README.md
+++ b/README.md
@@ -8,11 +8,13 @@
 [![Gitpod](https://camo.githubusercontent.com/1eb1ddfea6092593649f0117f7262ffa8fbd3017/68747470733a2f2f676974706f642e696f2f627574746f6e2f6f70656e2d696e2d676974706f642e737667)](https://gitpod-referer.now.sh/api/gitpod-referer-redirect)
 
 ## [EN] Introduction
+
 OpenFisca is a versatile microsimulation free software. This repository contains the OpenFisca model of the French tax and benefit system. Therefore, the working language here is French. You can however check the [general OpenFisca documentation](https://openfisca.org/doc/) in English!
 > We host a public instance of of the [OpenFisca-France Web API](https://api.fr.openfisca.org/latest/). Learn more about its endpoint in the [Swagger documentation](https://legislation.fr.openfisca.org/swagger).
 > If you need to run large amount of calculations, or add extensions, you should [host your own instance](#servez-openfisca-france-avec-lapi-web-openfisca).
 
 ## [FR] Introduction
+
 [OpenFisca](https://www.openfisca.fr/) est un logiciel libre de micro-simulation. Ce dépôt contient la modélisation du système social et fiscal français. Pour plus d'information sur les fonctionnalités et la manière d'utiliser OpenFisca, vous pouvez consulter la [documentation générale](https://openfisca.org/doc/).
 > Nous mettons à disposition une instance publique de [l'API Web OpenFisca-France](https://api.fr.openfisca.org/latest/). Découvrez ses capacité sur sa [documentation Swagger](https://legislation.fr.openfisca.org/swagger).
 > Si vous avez besoin de réaliser un grand nombre de calculs ou d'ajouter des extensions, vous pouvez [servir votre propre instance](#servez-openfisca-france-avec-lapi-web-openfisca).
@@ -31,7 +33,7 @@ L'ensembles des endpoints sont décrits dans la [documentation Swagger](https://
 
 ## Installation
 
-Ce paquet requiert [Python 3.7](https://www.python.org/downloads/release/python-370/) et [pip](https://pip.pypa.io/en/stable/installing/) ou [conda](https://www.anaconda.com/products/individual).
+Ce paquet requiert [Python 3.9](https://www.python.org/downloads/release/python-390/) et [pip](https://pip.pypa.io/en/stable/installing/) ou [conda](https://www.anaconda.com/products/individual).
 
 Plateformes supportées :
 - distributions GNU/Linux (en particulier Debian and Ubuntu) ;
@@ -50,7 +52,7 @@ Nous recommandons l'utilisation d'un [environnement virtuel](https://virtualenv.
 Pour installer Pew, lancez une fenêtre de terminal et suivez ces instructions :
 
 ```sh
-python --version # Python 3.7.0 ou plus récent devrait être installé sur votre ordinateur.
+python --version # Python 3.9.0 ou plus récent devrait être installé sur votre ordinateur.
 # Si non, téléchargez-le sur http://www.python.org et téléchargez pip.
 ```
 
@@ -58,10 +60,10 @@ python --version # Python 3.7.0 ou plus récent devrait être installé sur votr
 pip install --upgrade pip
 pip install pew
 ```
-Créez un nouveau _virtualenv_ nommé **openfisca** et configurez-le avec python 3.7 :
+Créez un nouveau _virtualenv_ nommé **openfisca** et configurez-le avec python 3.9 :
 
 ```sh
-pew new openfisca --python=python3.7
+pew new openfisca --python=python3.9
 # Si demandé, répondez "Y" à la question sur la modification du fichier de configuration de votre shell
 ```
 Le  _virtualenv_  **openfisca** sera alors activé, c'est-à-dire que les commandes suivantes s'exécuteront directement dans l'environnement virtuel. Vous verrez dans votre terminal :
@@ -94,8 +96,8 @@ Pour pouvoir modifier OpenFisca-France, consultez l'[Installation avancée](#b-i
 Dans votre _virtualenv_, vérifiez les pré-requis :
 
 ```sh
-python --version  # Devrait afficher "Python 3.7.xx".
-#Si non, vérifiez que vous passez --python=python3.7 lors de la création de votre environnement virtuel.
+python --version  # Devrait afficher "Python 3.9.xx".
+#Si non, vérifiez que vous passez --python=python3.9 lors de la création de votre environnement virtuel.
 ```
 
 ```sh
@@ -136,12 +138,12 @@ Dans votre _virtualenv_, assurez-vous que vous êtes dans le répertoire où vou
 Vérifiez les pré-requis :
 
 ```sh
-python --version  # Devrait afficher "Python 3.7.xx".
-#Si non, vérifiez que vous passez --python=python3.7 lors de la création de votre environnement virtuel.
+python --version  # Devrait afficher "Python 3.9.xx".
+#Si non, vérifiez que vous passez --python=python3.9 lors de la création de votre environnement virtuel.
 ```
 
 ```sh
-pip --version  # Devrait afficher au moins 9.0.
+pip --version  # Devrait afficher au moins 23.0.
 #Si non, exécutez "pip install --upgrade pip".
 ```
 
@@ -175,7 +177,7 @@ Voici les étapes à suivre :
 - Depuis le menu démarrer, exécuter `Anaconda Powershell Prompt`. Ou utiliser votre shell préféré avec Miniconda, il vous faudra peut-être utiliser la commande `conda init`, mais conda vous le dira.
 - Exécuter les commandes suivantes dans le shell:
   - Ajouter `conda-forge` comme channel par défaut : `conda config --add channels conda-forge && conda config --set channel_priority strict `
-  - Créer un environnement virtuel dédié : `conda create --name openfisca python=3.7`
+  - Créer un environnement virtuel dédié : `conda create --name openfisca python=3.9`
   - Activer l'environnement : `conda activate openfisca`
   - Installer OpenFisca : `conda install openfisca-france`
 
diff --git a/openfisca_france/model/base.py b/openfisca_france/model/base.py
index 56eabfc101..146824bdf5 100644
--- a/openfisca_france/model/base.py
+++ b/openfisca_france/model/base.py
@@ -1,6 +1,10 @@
 from openfisca_core.model_api import *
 from openfisca_france.entities import Famille, FoyerFiscal, Individu, Menage  # noqa F401
 
+
+AGE_INT_MINIMUM = -9999
+
+
 # Enums commonly used through the legislation
 
 
diff --git a/openfisca_france/model/prelevements_obligatoires/impot_revenu/ir.py b/openfisca_france/model/prelevements_obligatoires/impot_revenu/ir.py
index 19732b140a..533d37ed32 100644
--- a/openfisca_france/model/prelevements_obligatoires/impot_revenu/ir.py
+++ b/openfisca_france/model/prelevements_obligatoires/impot_revenu/ir.py
@@ -42,7 +42,7 @@ class jour_xyz(Variable):
 class age(Variable):
     unit = 'years'
     value_type = int
-    default_value = -9999
+    default_value = AGE_INT_MINIMUM
     entity = Individu
     label = 'Âge (en années) au premier jour du mois'
     definition_period = MONTH
@@ -81,7 +81,7 @@ def formula(individu, period, parameters):
 
 class age_en_mois(Variable):
     value_type = int
-    default_value = -9999
+    default_value = AGE_INT_MINIMUM
     unit = 'months'
     entity = Individu
     label = 'Âge (en mois)'
@@ -2566,7 +2566,7 @@ def abat_rpns(rev, P):
         return min_(
             f5ht + f5it + f5jt + f5kt + f5lt + f5mt,
             abat_rpns(mncn_impo, specialbnc.services) + mncn_pvct + cncn_aimp + (1 + cga) * cncn_bene
-            )  #  TODO check !
+            )  # TODO check !
 
 
 class defmeu(Variable):
@@ -2968,7 +2968,7 @@ def formula(individu, period, parameters):
         aacc_defn = individu('aacc_defn', period)
         aacc_defs = individu('aacc_defs', period)
         aacc_timp = max_(0, aacc_impn - aacc_defn - aacc_defs)
-        return(aacc_timp)
+        return aacc_timp
 
     def formula_2009_01_01(individu, period, parameters):
         aacc_impn = individu('aacc_impn', period)
@@ -2976,14 +2976,14 @@ def formula_2009_01_01(individu, period, parameters):
         aacc_defn = individu('aacc_defn', period)
         aacc_defs = individu('aacc_defs', period)
         aacc_timp = max_(0, aacc_impn + max_(0, - alnp_defs) - aacc_defn - aacc_defs)
-        return(aacc_timp)
+        return aacc_timp
 
     def formula_2010_01_01(individu, period, parameters):
         aacc_impn = individu('aacc_impn', period)
         alnp_defs = individu('alnp_defs', period)
         aacc_defn = individu('aacc_defn', period)
         aacc_timp = max_(0, aacc_impn + max_(0, - alnp_defs) - aacc_defn)
-        return(aacc_timp)
+        return aacc_timp
 
     def formula_2011_01_01(individu, period, parameters):
         aacc_impn = individu('aacc_impn', period)
@@ -3006,7 +3006,7 @@ def formula_2011_01_01(individu, period, parameters):
                 + max_(0, - alnp_defs) - aacc_defn
                 )
             )
-        return(aacc_timp)
+        return aacc_timp
 
     def formula_2012_01_01(individu, period, parameters):
         aacc_impn = individu('aacc_impn', period)
@@ -3035,7 +3035,7 @@ def formula_2012_01_01(individu, period, parameters):
                 + max_(0, nacc_defs - alnp_defs) - aacc_defn
                 )
             )
-        return(aacc_timp)
+        return aacc_timp
 
     def formula_2017_01_01(individu, period, parameters):
         aacc_impn = individu('aacc_impn', period)
@@ -3069,7 +3069,7 @@ def formula_2017_01_01(individu, period, parameters):
                 + max_(0, nacc_defs - alnp_defs) - aacc_defn
                 )
             )
-        return(aacc_timp)
+        return aacc_timp
 
 
 class atimp(Variable):
@@ -3094,7 +3094,7 @@ def formula(individu, period, parameters):
         abnc_timp = abnc_impo - abnc_defi
         # Total
         atimp = arag_impg + abic_timp + aacc_timp + abnc_timp
-        return(atimp)
+        return atimp
 
     def formula_2010_01_01(individu, period, parameters):
         abic_impn = individu('abic_impn', period)
@@ -3110,7 +3110,7 @@ def formula_2010_01_01(individu, period, parameters):
         abnc_timp = abnc_impo - abnc_defi
         # Total
         atimp = arag_impg + abic_timp + aacc_timp + abnc_timp
-        return(atimp)
+        return atimp
 
 
 class nbnc_timp(Variable):
@@ -3124,7 +3124,7 @@ def formula(individu, period, parameters):
         nbnc_defi = individu('nbnc_defi', period)
         # regime de la déclaration contrôlée ne bénéficiant pas de l'abattement association agréée
         nbnc_timp = nbnc_impo - nbnc_defi
-        return(nbnc_timp)
+        return nbnc_timp
 
 
 class nacc_timp(Variable):
@@ -3138,7 +3138,7 @@ def formula(individu, period, parameters):
         nacc_defn = individu('nacc_defn', period)
         # Régime du bénéfice réel ne bénéficiant pas de l'abattement CGA
         nacc_timp = max_(0, nacc_impn - nacc_defn)
-        return(nacc_timp)
+        return nacc_timp
 
 
 class ntimp(Variable):
@@ -3157,7 +3157,7 @@ def formula(individu, period, parameters):
         # Régime du bénéfice réel ne bénéficiant pas de l'abattement CGA
         nbic_timp = (nbic_impn + nbic_imps) - (nbic_defn + nbic_defs)
         ntimp = nacc_timp + nbnc_timp + nbic_timp
-        return(ntimp)
+        return ntimp
 
     def formula_2006_01_01(individu, period, parameters):
         nbic_impn = individu('nbic_impn', period)
@@ -3172,7 +3172,7 @@ def formula_2006_01_01(individu, period, parameters):
         nbic_timp = (nbic_impn + nbic_imps) - (nbic_defn + nbic_defs)
         cncn_timp = max_(0, cncn_bene - cncn_defi)
         ntimp = nbic_timp + nacc_timp + nbnc_timp + cncn_timp
-        return(ntimp)
+        return ntimp
 
     def formula_2007_01_01(individu, period, parameters):
         # Moyenne triennale
@@ -3189,7 +3189,7 @@ def formula_2007_01_01(individu, period, parameters):
         nbic_timp = (nbic_impn + nbic_imps) - (nbic_defn + nbic_defs)
         cncn_timp = max_(0, cncn_bene - cncn_defi)
         ntimp = nrag_impg + nbic_timp + nacc_timp + cncn_timp + nbnc_timp
-        return(ntimp)
+        return ntimp
 
     def formula_2010_01_01(individu, period, parameters):
         nrag_impg = individu('nrag_impg', period)
@@ -3203,7 +3203,7 @@ def formula_2010_01_01(individu, period, parameters):
         nbic_timp = nbic_impn - nbic_defn
         cncn_timp = max_(0, cncn_bene - cncn_defi)
         ntimp = nrag_impg + nbic_timp + nacc_timp + cncn_timp + nbnc_timp
-        return(ntimp)
+        return ntimp
 
 
 class revenu_non_salarie(Variable):
@@ -3224,7 +3224,7 @@ def formula(individu, period, parameters):
         majo_cga = max_(0, cga_taux2 * (ntimp + rpns_frag))  # Pour ne pas avoir à majorer les déficits
         def_agri = f5sq + arag_defi + (1 + cga_taux2) * nrag_defi
         revenus_non_salaries = rpns_frag + frag_fore + atimp + ntimp + majo_cga - def_agri
-        return(revenus_non_salaries)
+        return revenus_non_salaries
 
     def formula_2016_01_01(individu, period, parameters):
         rpns_mrag = individu('rpns_revenus_microBA_agricole', period)
@@ -3238,7 +3238,7 @@ def formula_2016_01_01(individu, period, parameters):
         majo_cga = max_(0, cga_taux2 * ntimp)  # Pour ne pas avoir à majorer les déficits
         def_agri = f5sq + arag_defi + (1 + cga_taux2) * nrag_defi
         revenus_non_salaries = rpns_mrag + coupe_bois + atimp + ntimp + majo_cga - def_agri
-        return(revenus_non_salaries)
+        return revenus_non_salaries
 
 
 class locations_pro(Variable):
@@ -3251,11 +3251,11 @@ def formula_2009_01_01(individu, period, parameters):
         abic_impm = individu('abic_impm', period)
         abic_defm = individu('abic_defm', period)
         alnp_imps = individu('alnp_imps', period)
-        return(abic_impm - abic_defm + alnp_imps)
+        return abic_impm - abic_defm + alnp_imps
 
     def formula_2016_01_01(individu, period, parameters):
         alnp_imps = individu('alnp_imps', period)
-        return(alnp_imps)
+        return alnp_imps
 
 
 class rpns_imposables(Variable):
diff --git a/openfisca_france/model/prelevements_obligatoires/prelevements_sociaux/cotisations_sociales/allegements.py b/openfisca_france/model/prelevements_obligatoires/prelevements_sociaux/cotisations_sociales/allegements.py
index 99879ac121..b214b1cd5d 100644
--- a/openfisca_france/model/prelevements_obligatoires/prelevements_sociaux/cotisations_sociales/allegements.py
+++ b/openfisca_france/model/prelevements_obligatoires/prelevements_sociaux/cotisations_sociales/allegements.py
@@ -2,6 +2,8 @@
 
 from numpy import busday_count, datetime64, logical_or as or_, logical_and as and_, timedelta64
 
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import *
 
 log = logging.getLogger(__name__)
@@ -537,7 +539,7 @@ def compute_allegement_anticipe(individu, period, parameters, variable_name, com
     if period.start.month == 12:
         cumul = individu(
             variable_name,
-            period.start.offset('first-of', 'year').period('month', 11), options = [ADD])
+            Period(('month', period.start.offset('first-of', 'year'), 11)), options = [ADD])
         return compute_function(
             individu, period.this_year, parameters
             ) - cumul
@@ -548,8 +550,8 @@ def compute_allegement_progressif(individu, period, parameters, variable_name, c
         return compute_function(individu, period.first_month, parameters)
 
     if period.start.month > 1:
-        up_to_this_month = period.start.offset('first-of', 'year').period('month', period.start.month)
-        up_to_previous_month = period.start.offset('first-of', 'year').period('month', period.start.month - 1)
+        up_to_this_month = Period(('month', period.start.offset('first-of', 'year'), period.start.month))
+        up_to_previous_month = Period(('month', period.start.offset('first-of', 'year'), period.start.month - 1))
         cumul = individu(variable_name, up_to_previous_month, options = [ADD])
         return compute_function(individu, up_to_this_month, parameters) - cumul
 
diff --git a/openfisca_france/model/prelevements_obligatoires/prelevements_sociaux/cotisations_sociales/base.py b/openfisca_france/model/prelevements_obligatoires/prelevements_sociaux/cotisations_sociales/base.py
index fbb9be833f..174c8045d3 100644
--- a/openfisca_france/model/prelevements_obligatoires/prelevements_sociaux/cotisations_sociales/base.py
+++ b/openfisca_france/model/prelevements_obligatoires/prelevements_sociaux/cotisations_sociales/base.py
@@ -1,3 +1,5 @@
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import *
 
 
@@ -271,7 +273,7 @@ def iter_cotisations():
                 # FIXME: dirty fix since public_titulaire_militaire does not exist
                 if categorie_salarie_type.name == 'public_titulaire_militaire':
                     continue
-                raise(e)
+                raise e
 
             if bareme_name in cotisations_by_categorie_salarie[categorie_salarie_type.name]:
                 bareme = categorie_salarie_baremes[bareme_name]
@@ -371,8 +373,10 @@ def compute_cotisation_anticipee(individu, period, parameters, cotisation_type =
             bareme_name = bareme_name,
             )
     if period.start.month == 12:
-        cumul = individu(variable_name, period.start.offset('first-of', 'month').offset(
-            -11, 'month').period('month', 11), options = [ADD])
+        cumul = individu(
+            variable_name,
+            Period(('month', period.start.offset('first-of', 'month').offset(-11, 'month'), 11)),
+            options = [ADD])
         # December variable_name depends on variable_name in the past 11 months.
         # We need to explicitely allow this recursion.
 
diff --git a/openfisca_france/model/prelevements_obligatoires/taxe_habitation/taxe_habitation.py b/openfisca_france/model/prelevements_obligatoires/taxe_habitation/taxe_habitation.py
index bf0cadcde8..2f6e32c41d 100644
--- a/openfisca_france/model/prelevements_obligatoires/taxe_habitation/taxe_habitation.py
+++ b/openfisca_france/model/prelevements_obligatoires/taxe_habitation/taxe_habitation.py
@@ -1,3 +1,5 @@
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import *
 
 
@@ -333,7 +335,7 @@ def formula_2017_01_01(menage, period, parameters):
         taux_th_commune = menage('taux_th_commune', period)
         taux_th_epci = menage('taux_th_epci', period)
         ecart_avec_2000 = period.start.offset('first-of', 'year').year - 2000
-        annee_2000 = period.start.offset('first-of', 'year').period('year').offset(-ecart_avec_2000)
+        annee_2000 = Period(('year', period.start.offset('first-of', 'year'), 1)).offset(-ecart_avec_2000)
         taux_th_commune_2000 = menage('taux_th_commune', annee_2000)
         taux_th_epci_2000 = menage('taux_th_epci', annee_2000)
 
diff --git a/openfisca_france/model/prestations/agepi.py b/openfisca_france/model/prestations/agepi.py
index aea93b0287..ef3a1ac84b 100644
--- a/openfisca_france/model/prestations/agepi.py
+++ b/openfisca_france/model/prestations/agepi.py
@@ -1,5 +1,7 @@
 from numpy import fabs, timedelta64
 
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import Famille, Individu, Variable, Enum, MONTH, ADD,\
     set_input_dispatch_by_period, set_input_divide_by_period, date, min_, not_
 from openfisca_france.model.revenus.activite.salarie import TypesContrat, TypesLieuEmploiFormation,\
@@ -83,7 +85,7 @@ def formula_2014_01_20(individu, period, parameters):
         condition_nb_enfants = individu.famille('agepi_nbenf', period) > 0
 
         # L'individu n'a pas touché l'AGEPI dans les 12 derniers mois (condition de durée entre faits générateurs)
-        annee_glissante = period.start.period('year').offset(-1).offset(-1, 'month')
+        annee_glissante = Period(('year', period.start, 1)).offset(-1).offset(-1, 'month')
         agepi_non_percues = not_(individu('agepi', annee_glissante, options=[ADD]))
 
         # L'individu est inscrit en catégorie 1, 2, 3, 4 "stagiaire de la formation professionnelle" ou 5 "contrat aidé"
diff --git a/openfisca_france/model/prestations/aide_mobilite.py b/openfisca_france/model/prestations/aide_mobilite.py
index a7772c2ffe..63f0e6f671 100644
--- a/openfisca_france/model/prestations/aide_mobilite.py
+++ b/openfisca_france/model/prestations/aide_mobilite.py
@@ -1,4 +1,7 @@
 from numpy import fabs, timedelta64
+
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import Individu, Variable, MONTH, Enum, not_, ADD,\
     set_input_dispatch_by_period, set_input_divide_by_period, min_, date
 from openfisca_france.model.caracteristiques_socio_demographiques.logement import TypesLieuResidence
@@ -326,7 +329,7 @@ def formula_2021_06_09(individu, period, parameters):
         eligibilite_amob = individu('aide_mobilite_eligible', period)
         parametres_amob = parameters(period).prestations_sociales.aide_mobilite
 
-        annee_glissante = period.start.period('year').offset(-1)
+        annee_glissante = Period(('year', period.start, 1)).offset(-1)
 
         aide_mobilite_12_derniers_mois = individu('aide_mobilite', annee_glissante, options=[ADD])
 
diff --git a/openfisca_france/model/prestations/aides_exceptionnelles/indemnite_inflation.py b/openfisca_france/model/prestations/aides_exceptionnelles/indemnite_inflation.py
index 799808991b..29508eb2e9 100644
--- a/openfisca_france/model/prestations/aides_exceptionnelles/indemnite_inflation.py
+++ b/openfisca_france/model/prestations/aides_exceptionnelles/indemnite_inflation.py
@@ -1,5 +1,7 @@
-from openfisca_france.model.base import *
 from openfisca_core import periods
+
+from openfisca_france.model.base import *
+
 from numpy import logical_or as or_, logical_and as and_
 
 # Les éligibilités séparées de l'indemnité inflation
diff --git a/openfisca_france/model/prestations/aides_logement.py b/openfisca_france/model/prestations/aides_logement.py
index 8154196b8e..a357421a11 100644
--- a/openfisca_france/model/prestations/aides_logement.py
+++ b/openfisca_france/model/prestations/aides_logement.py
@@ -7,9 +7,9 @@
 
 from numpy import ceil, datetime64, fromiter, int16, logical_or as or_, logical_and as and_, logical_not as not_
 
-import openfisca_france
-from openfisca_core.periods import Instant
+from openfisca_core.periods import Instant, Period
 
+import openfisca_france
 from openfisca_france.model.base import *
 from openfisca_france.model.revenus.activite.salarie import TypesConges
 from openfisca_france.model.prestations.prestations_familiales.base_ressource import nb_enf
@@ -566,7 +566,7 @@ class aide_logement_base_ressources_individu(Variable):
 
     def formula_2021_01_01(individu, period, parameters):
         period_frais = period.last_year
-        annee_glissante = period.start.period('year').offset(-1).offset(-1, 'month')
+        annee_glissante = Period(('year', period.start, 1)).offset(-1).offset(-1, 'month')
 
         salaire_imposable = individu('salaire_imposable', annee_glissante, options=[ADD])
         chomage_imposable = individu('chomage_imposable', annee_glissante, options=[ADD])
diff --git a/openfisca_france/model/prestations/autonomie.py b/openfisca_france/model/prestations/autonomie.py
index 50e7ac90f8..c5833d397b 100644
--- a/openfisca_france/model/prestations/autonomie.py
+++ b/openfisca_france/model/prestations/autonomie.py
@@ -1,3 +1,5 @@
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import *
 
 
@@ -133,7 +135,7 @@ class apa_eligibilite(Variable):
     set_input = set_input_dispatch_by_period
 
     def formula_2002(individu, period, parameters):
-        period = period.start.offset('first-of', 'month').period('month')
+        period = Period(('month', period.start.offset('first-of', 'month'), 1))
         parameters = parameters(period).prestations_sociales.prestations_etat_de_sante.perte_autonomie_personnes_agees
         age = individu('age', period)
         apa_age_min = parameters.apa_domicile.condition_age
@@ -172,7 +174,7 @@ class apa_domicile(Variable):
     set_input = set_input_divide_by_period
 
     def formula_2002(individu, period, parameters):
-        period = period.start.offset('first-of', 'month').period('month')
+        period = Period(('month', period.start.offset('first-of', 'month'), 1))
         apa_domicile = parameters(period).prestations_sociales.prestations_etat_de_sante.perte_autonomie_personnes_agees.apa_domicile
         apa_eligibilite = individu('apa_eligibilite', period)
         smic_brut_horaire = parameters(period).marche_travail.salaire_minimum.smic.smic_b_horaire
@@ -193,7 +195,7 @@ class apa_etablissement(Variable):
     set_input = set_input_divide_by_period
 
     def formula_2002(individu, period, parameters):
-        period = period.start.offset('first-of', 'month').period('month')
+        period = Period(('month', period.start.offset('first-of', 'month'), 1))
         perte_autonomie_personnes_agees = parameters(period).prestations_sociales.prestations_etat_de_sante.perte_autonomie_personnes_agees
         smic_brut_horaire = parameters(period).marche_travail.salaire_minimum.smic.smic_b_horaire
         seuil_non_versement = perte_autonomie_personnes_agees.apa_institution.seuil_versement_en_part_smic_brut_horaire * smic_brut_horaire
@@ -350,7 +352,7 @@ class apa_urgence_institution(Variable):
     set_input = set_input_divide_by_period
 
     def formula_2002(individu, period, parameters):
-        period = period.start.offset('first-of', 'month').period('month')
+        period = Period(('month', period.start.offset('first-of', 'month'), 1))
         dependance_tarif_etablissement_gir_1_2 = individu('dependance_tarif_etablissement_gir_1_2', period)
         part_urgence_institution = parameters(period).prestations_sociales.prestations_etat_de_sante.perte_autonomie_personnes_agees.apa_institution.part_tarif_dependance
         apa_urgence_institution = part_urgence_institution * dependance_tarif_etablissement_gir_1_2
diff --git a/openfisca_france/model/prestations/jeunes/contrat_engagement_jeune.py b/openfisca_france/model/prestations/jeunes/contrat_engagement_jeune.py
index d70afec1aa..bff8be3f8c 100644
--- a/openfisca_france/model/prestations/jeunes/contrat_engagement_jeune.py
+++ b/openfisca_france/model/prestations/jeunes/contrat_engagement_jeune.py
@@ -1,3 +1,5 @@
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import *  # noqa analysis:ignore
 from numpy import (
     logical_not as not_,
@@ -19,7 +21,7 @@ class contrat_engagement_jeune_montant_forfaitaire(Variable):
     def formula_2022_03_01(individu, period, parameters):
         parameters_montants = parameters(period).prestations_sociales.aides_jeunes.contrat_engagement_jeune.montants
         majeur = individu('majeur', period)
-        previous_year = period.start.period('year').offset(-1)
+        previous_year = Period(('year', period.start, 1)).offset(-1)
         tranche = individu.foyer_fiscal('ir_tranche', previous_year)
 
         montant_forfaitaire = (
@@ -50,7 +52,7 @@ def formula_2022_03_01(individu, period, parameters):
         eligibilite_statut = activite != TypesActivite.etudiant
 
         # En fonction de l'imposition du foyer fiscal
-        previous_year = period.start.period('year').offset(-1)
+        previous_year = Period(('year', period.start, 1)).offset(-1)
         tranche = individu.foyer_fiscal('ir_tranche', previous_year)
         eligibilite_ir = (tranche <= 1)
 
diff --git a/openfisca_france/model/prestations/logement_social.py b/openfisca_france/model/prestations/logement_social.py
index 84fa73fd9e..6b04c9293a 100644
--- a/openfisca_france/model/prestations/logement_social.py
+++ b/openfisca_france/model/prestations/logement_social.py
@@ -1,7 +1,7 @@
 from numpy import isin, logical_not as not_, select
 
 from openfisca_core.indexed_enums import Enum
-from openfisca_core.periods import MONTH
+from openfisca_core.periods import MONTH, Period
 from openfisca_core.variables import Variable
 
 from openfisca_france.entities import Famille, Menage
@@ -172,7 +172,7 @@ class logement_social_eligible(Variable):
     def formula_2017(famille, period, parameters):
         parent_majeur = famille.any(famille.members('majeur', period), role = Famille.PARENT)
         logement_social_plafond_ressources = famille('logement_social_plafond_ressources', period)
-        rfr_n0 = famille.demandeur.foyer_fiscal('rfr', period.start.offset('first-of', 'year').period('year'))
+        rfr_n0 = famille.demandeur.foyer_fiscal('rfr', Period(('year', period.start.offset('first-of', 'year'), 1)))
         rfr_n1 = famille.demandeur.foyer_fiscal('rfr', period.last_year)
         rfr_n2 = famille.demandeur.foyer_fiscal('rfr', period.n_2)
 
diff --git a/openfisca_france/model/prestations/minima_sociaux/aah.py b/openfisca_france/model/prestations/minima_sociaux/aah.py
index f4c02d6e32..3c3ec5376c 100644
--- a/openfisca_france/model/prestations/minima_sociaux/aah.py
+++ b/openfisca_france/model/prestations/minima_sociaux/aah.py
@@ -1,3 +1,5 @@
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import *
 
 from numpy import datetime64
@@ -105,7 +107,7 @@ def assiette_revenu_activite_demandeur(revenus_demandeur):
             return (1 - aah.travail_ordinaire.abattement_30) * total_tranche1 + (1 - aah.travail_ordinaire.abattement_sup) * total_tranche2
 
         def base_ressource_eval_trim():
-            three_previous_months = period.first_month.start.period('month', 3).offset(-3)
+            three_previous_months = Period(('month', period.first_month.start, 3)).offset(-3)
             base_ressource_activite = individu('aah_base_ressources_activite_eval_trimestrielle', period) - individu('aah_base_ressources_activite_milieu_protege', three_previous_months, options = [ADD])
             base_ressource_hors_activite = individu('aah_base_ressources_hors_activite_eval_trimestrielle', period) + individu('aah_base_ressources_activite_milieu_protege', three_previous_months, options = [ADD])
 
@@ -151,7 +153,7 @@ def assiette_revenu_activite_demandeur(revenus_demandeur):
             return (1 - aah.travail_ordinaire.abattement_30) * total_tranche1 + (1 - aah.travail_ordinaire.abattement_sup) * total_tranche2
 
         def base_ressource_eval_trim():
-            three_previous_months = period.first_month.start.period('month', 3).offset(-3)
+            three_previous_months = Period(('month', period.first_month.start, 3)).offset(-3)
             base_ressource_activite = individu('aah_base_ressources_activite_eval_trimestrielle', period) - individu('aah_base_ressources_activite_milieu_protege', three_previous_months, options = [ADD])
             base_ressource_hors_activite = individu('aah_base_ressources_hors_activite_eval_trimestrielle', period) + individu('aah_base_ressources_activite_milieu_protege', three_previous_months, options = [ADD])
 
@@ -192,7 +194,7 @@ def assiette_revenu_activite_demandeur(revenus_demandeur):
             return (1 - aah.travail_ordinaire.abattement_30) * total_tranche1 + (1 - aah.travail_ordinaire.abattement_sup) * total_tranche2
 
         def base_ressource_eval_trim():
-            three_previous_months = period.first_month.start.period('month', 3).offset(-3)
+            three_previous_months = Period(('month', period.first_month.start, 3)).offset(-3)
             base_ressource_activite = individu('aah_base_ressources_activite_eval_trimestrielle', period) - individu('aah_base_ressources_activite_milieu_protege', three_previous_months, options = [ADD])
             base_ressource_hors_activite = individu('aah_base_ressources_hors_activite_eval_trimestrielle', period) + individu('aah_base_ressources_activite_milieu_protege', three_previous_months, options = [ADD])
 
@@ -239,7 +241,7 @@ class aah_base_ressources_activite_eval_trimestrielle(Variable):
 
     def formula(individu, period):
         period = period.first_month
-        three_previous_months = period.start.period('month', 3).offset(-3)
+        three_previous_months = Period(('month', period.start, 3)).offset(-3)
         last_year = period.last_year
 
         ressources_a_inclure = [
@@ -299,7 +301,7 @@ class aah_base_ressources_hors_activite_eval_trimestrielle(Variable):
 
     def formula(individu, period):
         period = period.first_month
-        three_previous_months = period.start.period('month', 3).offset(-3)
+        three_previous_months = Period(('month', period.start, 3)).offset(-3)
 
         ressources_a_inclure = [
             'asi',
@@ -564,7 +566,7 @@ class eligibilite_caah(Variable):
     set_input = set_input_dispatch_by_period
 
     def formula_2015_07_01(individu, period, parameters):
-        annee_precedente = period.start.period('year').offset(-1)
+        annee_precedente = Period(('year', period.start, 1)).offset(-1)
         prestations = parameters(period).prestations_sociales
         taux_incapacite_min = prestations.prestations_etat_de_sante.invalidite.aah.taux_capacite.taux_incapacite
         aah = individu('aah', period)
@@ -606,7 +608,7 @@ def formula_2015_07_01(individu, period, parameters):
 
     def formula_2005_07_01(individu, period, parameters):
         invalidite = parameters(period).prestations_sociales.prestations_etat_de_sante.invalidite
-        annee_precedente = period.start.period('year').offset(-1)
+        annee_precedente = Period(('year', period.start, 1)).offset(-1)
         activite_12_mois = individu('salaire_imposable', annee_precedente, options = [ADD]) + individu('rpns_imposables', annee_precedente)
 
         garantie_ressources = invalidite.caah.garantie_ressources
diff --git a/openfisca_france/model/prestations/minima_sociaux/asi_aspa.py b/openfisca_france/model/prestations/minima_sociaux/asi_aspa.py
index 5a691c3ca5..44f675b56e 100644
--- a/openfisca_france/model/prestations/minima_sociaux/asi_aspa.py
+++ b/openfisca_france/model/prestations/minima_sociaux/asi_aspa.py
@@ -1,5 +1,7 @@
 from numpy import abs as abs_, logical_or as or_
 
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import *
 
 
@@ -147,7 +149,7 @@ class asi_eligibilite(Variable):
     set_input = set_input_dispatch_by_period
 
     def formula(individu, period):
-        last_month = period.start.period('month').offset(-1)
+        last_month = Period(('month', period.start, 1)).offset(-1)
 
         non_eligible_aspa = not_(individu('aspa_eligibilite', period))
         touche_pension_invalidite = individu('pensions_invalidite', period) > 0
diff --git a/openfisca_france/model/prestations/minima_sociaux/ass.py b/openfisca_france/model/prestations/minima_sociaux/ass.py
index 78201cc4b5..faa8b74ae1 100644
--- a/openfisca_france/model/prestations/minima_sociaux/ass.py
+++ b/openfisca_france/model/prestations/minima_sociaux/ass.py
@@ -1,5 +1,7 @@
 from numpy import absolute as abs_, logical_and as and_
 
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import *
 
 
@@ -79,7 +81,7 @@ class ass_base_ressources_individu(Variable):
 
     def formula(individu, period, parameters):
         # Rolling year
-        previous_year = period.start.period('year').offset(-1)
+        previous_year = Period(('year', period.start, 1)).offset(-1)
         # N-1
         last_year = period.last_year
 
@@ -130,9 +132,9 @@ class ass_base_ressources_conjoint(Variable):
 
     def formula(individu, period, parameters):
         # Rolling year
-        previous_year = period.start.period('year').offset(-1)
+        previous_year = Period(('year', period.start, 1)).offset(-1)
 
-        last_month = period.start.period('month').offset(-1)
+        last_month = Period(('month', period.start, 1)).offset(-1)
 
         ass_base_ressources_individu = individu('ass_base_ressources_individu', period)
         chomage_net_interrompue = individu('chomage_net', last_month) == 0
@@ -147,14 +149,14 @@ def formula(individu, period, parameters):
 
 
 def calculateWithAbatement(individu, parameters, period, ressourceName):
-    last_month = period.start.period('month').offset(-1)
+    last_month = Period(('month', period.start, 1)).offset(-1)
     has_ressources_substitution = (
         individu('chomage_net', last_month)
         + individu('indemnites_journalieres', last_month)
         + individu('retraite_nette', last_month)
         ) > 0
     # Rolling year
-    previous_year = period.start.period('year').offset(-1)
+    previous_year = Period(('year', period.start, 1)).offset(-1)
 
     ressource_year = individu(ressourceName, previous_year, options=[ADD])
     ressource_last_month = individu(ressourceName, last_month)
diff --git a/openfisca_france/model/prestations/minima_sociaux/cs/eligibilite.py b/openfisca_france/model/prestations/minima_sociaux/cs/eligibilite.py
index 4875139548..6903afb120 100644
--- a/openfisca_france/model/prestations/minima_sociaux/cs/eligibilite.py
+++ b/openfisca_france/model/prestations/minima_sociaux/cs/eligibilite.py
@@ -1,4 +1,7 @@
 from numpy import logical_not as not_
+
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import Variable, Famille, MONTH, ADD, set_input_dispatch_by_period
 
 
@@ -10,7 +13,7 @@ class css_cmu_acs_eligibilite(Variable):
     set_input = set_input_dispatch_by_period
 
     def formula(famille, period, parameters):
-        previous_year = period.start.period('year').offset(-1)
+        previous_year = Period(('year', period.start, 1)).offset(-1)
         this_year = period.this_year
         age_min = parameters(period).prestations_sociales.solidarite_insertion.minima_sociaux.cs.cmu.age_limite_pac
         nb_enfants = famille('cmu_nb_pac', period)
diff --git a/openfisca_france/model/prestations/minima_sociaux/cs/ressources.py b/openfisca_france/model/prestations/minima_sociaux/cs/ressources.py
index cb50472c65..6699e6ead0 100644
--- a/openfisca_france/model/prestations/minima_sociaux/cs/ressources.py
+++ b/openfisca_france/model/prestations/minima_sociaux/cs/ressources.py
@@ -1,5 +1,7 @@
 from numpy import absolute as abs_, logical_or as or_, logical_not as not_
 
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import (
     Variable,
     Individu,
@@ -29,7 +31,7 @@ class css_cmu_base_ressources_individu(Variable):
 
     def formula(individu, period, parameters):
         # Rolling year
-        previous_year = period.start.period('year').offset(-1)
+        previous_year = Period(('year', period.start, 1)).offset(-1)
         # N-1
         last_year = period.last_year
         last_month = period.last_month
@@ -93,7 +95,7 @@ class css_cmu_base_ressources(Variable):
     set_input = set_input_divide_by_period
 
     def formula(famille, period, parameters):
-        previous_year = period.start.period('year').offset(-1)
+        previous_year = Period(('year', period.start, 1)).offset(-1)
 
         ressources_famille_a_inclure = [
             'af',
diff --git a/openfisca_france/model/prestations/minima_sociaux/rsa.py b/openfisca_france/model/prestations/minima_sociaux/rsa.py
index 75f09d3590..f8a2617e86 100644
--- a/openfisca_france/model/prestations/minima_sociaux/rsa.py
+++ b/openfisca_france/model/prestations/minima_sociaux/rsa.py
@@ -1,6 +1,8 @@
 from numpy import datetime64, logical_and as and_, logical_or as or_
 
 from openfisca_core import periods
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import *
 from openfisca_france.model.prestations.prestations_familiales.base_ressource import nb_enf
 
@@ -960,7 +962,7 @@ class rsa_non_calculable_tns_individu(Variable):
     # En fait l'évaluation par le PCD est plutôt l'exception que la règle. En général on retient plutôt le bénéfice déclaré au FISC (après abattement forfaitaire ou réel).
 
     def formula(individu, period):
-        this_year_and_last_year = period.start.offset('first-of', 'year').period('year', 2).offset(-1)
+        this_year_and_last_year = Period(('year', period.start.offset('first-of', 'year'), 2)).offset(-1)
         rpns_benefice_exploitant_agricole = individu('rpns_benefice_exploitant_agricole', this_year_and_last_year, options = [ADD])
         rpns_micro_entreprise_chiffre_affaires = individu('rpns_micro_entreprise_chiffre_affaires', this_year_and_last_year, options = [ADD])
         rpns_autres_revenus = individu('rpns_autres_revenus', this_year_and_last_year, options = [ADD])
diff --git a/openfisca_france/model/prestations/prestations_familiales/af.py b/openfisca_france/model/prestations/prestations_familiales/af.py
index b469c9ae95..9f969c2e76 100644
--- a/openfisca_france/model/prestations/prestations_familiales/af.py
+++ b/openfisca_france/model/prestations/prestations_familiales/af.py
@@ -152,7 +152,7 @@ def formula_2015_07_01(famille, period, parameters):
 
 class af_age_aine(Variable):
     value_type = int
-    default_value = -9999
+    default_value = AGE_INT_MINIMUM
     entity = Famille
     label = "Allocations familiales - Âge de l'aîné des enfants éligibles"
     definition_period = MONTH
@@ -161,14 +161,11 @@ class af_age_aine(Variable):
 
     def formula(famille, period, parameters):
         af = parameters(period).prestations_sociales.prestations_familiales.prestations_generales.af
-
         age = famille.members('age', period)
         pfam_enfant_a_charge = famille.members('prestations_familiales_enfant_a_charge', period)
-
         condition_eligibilite = pfam_enfant_a_charge * (age <= af.af_cm.age2)
         age_enfants_eligiles = age * condition_eligibilite
-
-        return famille.max(age_enfants_eligiles, role = Famille.ENFANT)
+        return max_(famille.max(age_enfants_eligiles, role = Famille.ENFANT), AGE_INT_MINIMUM)  # max_ may return -inf, so negative caping by AGE_INT_MINIMUM is needed
 
 
 class af_majoration_enfant(Variable):
diff --git a/openfisca_france/model/prestations/prestations_familiales/ars.py b/openfisca_france/model/prestations/prestations_familiales/ars.py
index 27552b7a6a..4cd2943b70 100644
--- a/openfisca_france/model/prestations/prestations_familiales/ars.py
+++ b/openfisca_france/model/prestations/prestations_familiales/ars.py
@@ -1,4 +1,7 @@
 from numpy import logical_not as not_
+
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import *
 from openfisca_france.model.prestations.prestations_familiales.base_ressource import nb_enf
 
@@ -15,8 +18,8 @@ def formula(famille, period, parameters):
         Allocation de rentrée scolaire brute de CRDS
         '''
         janvier = period.first_month
-        octobre = period.start.offset('first-of', 'year').offset(9, 'month').period('month')
-        decembre = period.start.offset('first-of', 'year').offset(11, 'month').period('month')
+        octobre = Period(('month', period.start.offset('first-of', 'year').offset(9, 'month'), 1))
+        decembre = Period(('month', period.start.offset('first-of', 'year').offset(11, 'month'), 1))
         af_nbenf = famille('af_nbenf', octobre)
         base_ressources = famille('prestations_familiales_base_ressources', janvier)
         ars = parameters(octobre).prestations_sociales.prestations_familiales.education_presence_parentale.ars
diff --git a/openfisca_france/model/prestations/prestations_familiales/base_ressource.py b/openfisca_france/model/prestations/prestations_familiales/base_ressource.py
index 63527b5871..3722dcea4b 100644
--- a/openfisca_france/model/prestations/prestations_familiales/base_ressource.py
+++ b/openfisca_france/model/prestations/prestations_familiales/base_ressource.py
@@ -1,8 +1,8 @@
-from numpy import logical_or as or_
+from numpy import datetime64, logical_or as or_
 
-from openfisca_france.model.base import *
+from openfisca_core.periods import Period
 
-from numpy import datetime64
+from openfisca_france.model.base import *
 
 
 class autonomie_financiere(Variable):
@@ -18,7 +18,7 @@ class autonomie_financiere(Variable):
 
     def formula(individu, period, parameters):
         # D'après service-public.fr, la condition de dépassement du salaire plafonds n'est pas évalué de la même manière suivant si l'enfant est étudiant ou salarié/apprenti/stagiaire.
-        salaire_net_mensualise = individu('salaire_net', period.start.period('month', 6).offset(-6), options = [ADD]) / 6
+        salaire_net_mensualise = individu('salaire_net', Period(('month', period.start, 6)).offset(-6), options = [ADD]) / 6
 
         _P = parameters(period)
 
diff --git a/openfisca_france/model/revenus/activite/non_salarie.py b/openfisca_france/model/revenus/activite/non_salarie.py
index ca43f12240..87fed1d723 100644
--- a/openfisca_france/model/revenus/activite/non_salarie.py
+++ b/openfisca_france/model/revenus/activite/non_salarie.py
@@ -1,3 +1,5 @@
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import *
 
 
@@ -2086,7 +2088,7 @@ class travailleur_non_salarie(Variable):
     set_input = set_input_dispatch_by_period
 
     def formula(individu, period, parameters):
-        this_year_and_last_year = period.start.offset('first-of', 'year').period('year', 2).offset(-1)
+        this_year_and_last_year = Period(('year', period.start.offset('first-of', 'year'), 2)).offset(-1)
         rpns_auto_entrepreneur_chiffre_affaires = individu('rpns_auto_entrepreneur_chiffre_affaires', period) != 0
         rpns_micro_entreprise_chiffre_affaires = individu('rpns_micro_entreprise_chiffre_affaires', this_year_and_last_year, options = [ADD]) != 0
         rpns_autres_revenus = individu('rpns_autres_revenus', this_year_and_last_year, options = [ADD]) != 0
diff --git a/openfisca_france/model/revenus/activite/salarie.py b/openfisca_france/model/revenus/activite/salarie.py
index 1336ce0cb5..bc9afe9ae9 100644
--- a/openfisca_france/model/revenus/activite/salarie.py
+++ b/openfisca_france/model/revenus/activite/salarie.py
@@ -1,5 +1,8 @@
 from functools import partial
 from numpy import busday_count as original_busday_count, datetime64, timedelta64, where
+
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import *
 
 
@@ -707,7 +710,7 @@ class ppv_eligibilite_exceptionnelle(Variable):
     '''
 
     def formula_2022_07_01(individu, period, parameters):
-        annee_glissante = period.start.period('year').offset(-1)
+        annee_glissante = Period(('year', period.start, 1)).offset(-1)
         salaire_de_base_annuel = individu('salaire_de_base', annee_glissante, options=[ADD])
         smic_b_annuel = parameters(period).marche_travail.salaire_minimum.smic.smic_b_mensuel * 12
         quotite_de_travail = individu('quotite_de_travail', period, options=[ADD]) / 12
@@ -804,7 +807,7 @@ def formula_2019_01_01(individu, period, parameters):
         sinon
             Pas d'exonération
         '''
-        annee_glissante = period.start.period('year').offset(-1)
+        annee_glissante = Period(('year', period.start, 1)).offset(-1)
         salaire_de_base_annuel = individu('salaire_de_base', annee_glissante, options=[ADD])
         smic_b_annuel = parameters(period).marche_travail.salaire_minimum.smic.smic_b_mensuel * 12
         quotite_de_travail = individu('quotite_de_travail', period, options=[ADD]) / 12
@@ -1234,7 +1237,7 @@ class indice_majore(Variable):
     set_input = set_input_dispatch_by_period
 
     def formula(individu, period, parameters):
-        period = period.start.period('month').offset('first-of')
+        period = Period(('month', period.start, 1)).offset('first-of')
         categorie_salarie = individu('categorie_salarie', period)
         traitement_indiciaire_brut = individu('traitement_indiciaire_brut', period)
         traitement_annuel_brut = parameters(period).prestations_sociales.fonc.IM_100
@@ -1285,7 +1288,7 @@ def formula(famille, period, parameters):
             D'où l'introduction de cette variable alternative.
         '''
 
-        salaire_de_base_mensualise = famille.members('salaire_de_base', period.start.period('month', 6).offset(-6), options = [ADD])
+        salaire_de_base_mensualise = famille.members('salaire_de_base', Period(('month', period.start, 6)).offset(-6), options = [ADD])
         law = parameters(period)
         nbh_travaillees = 169
         smic_mensuel_brut = law.marche_travail.salaire_minimum.smic.smic_b_horaire * nbh_travaillees
diff --git a/openfisca_france/model/revenus/remplacement/rente_accident_travail.py b/openfisca_france/model/revenus/remplacement/rente_accident_travail.py
index 580d9163d3..8768295662 100644
--- a/openfisca_france/model/revenus/remplacement/rente_accident_travail.py
+++ b/openfisca_france/model/revenus/remplacement/rente_accident_travail.py
@@ -1,3 +1,5 @@
+from openfisca_core.periods import Period
+
 from openfisca_france.model.base import *
 
 
@@ -10,7 +12,7 @@ class rente_accident_travail(Variable):
     set_input = set_input_divide_by_period
 
     def formula(individu, period):
-        previous_year = period.start.period('year').offset(-1)
+        previous_year = Period(('year', period.start, 1)).offset(-1)
         non_salarie_agricole = individu('rpns_benefice_exploitant_agricole', previous_year, options=[ADD]) != 0
         rente_accident_travail_salarie = individu('rente_accident_travail_salarie', period)
         rente_accident_travail_exploitant_agricole = individu('rente_accident_travail_exploitant_agricole', period)
@@ -27,7 +29,7 @@ class rente_accident_travail_salarie(Variable):
     set_input = set_input_divide_by_period
 
     def formula(individu, period):
-        previous_year = period.start.period('year').offset(-1)
+        previous_year = Period(('year', period.start, 1)).offset(-1)
         salarie = individu('salaire_net', previous_year, options=[ADD]) != 0
         rente_accident_travail_rachat = individu('rente_accident_travail_rachat', period)
         taux_incapacite = individu('taux_accident_travail', period)
@@ -52,7 +54,7 @@ class rente_accident_travail_exploitant_agricole(Variable):
     set_input = set_input_divide_by_period
 
     def formula(individu, period):
-        previous_year = period.start.period('year').offset(-1)
+        previous_year = Period(('year', period.start, 1)).offset(-1)
         non_salarie_agricole = individu('rpns_benefice_exploitant_agricole', previous_year, options=[ADD]) != 0
         rente_accident_travail_rachat = individu('rente_accident_travail_rachat', period)
         taux_incapacite = individu('taux_accident_travail', period)
@@ -180,7 +182,7 @@ class rente_accident_travail_salaire_utile(Variable):
     set_input = set_input_divide_by_period
 
     def formula(individu, period, parameters):
-        previous_year = period.start.period('year').offset(-1)
+        previous_year = Period(('year', period.start, 1)).offset(-1)
         rente_at = parameters(period).prestations_sociales.solidarite_insertion.minima_sociaux.accident_travail.rente
 
         salaire_net = individu('salaire_net', previous_year, options=[ADD])
diff --git a/setup.py b/setup.py
index 17bee9718b..0a9eb1a3fa 100644
--- a/setup.py
+++ b/setup.py
@@ -1,6 +1,6 @@
 #! /usr/bin/env python
 
-from setuptools import setup, find_packages
+from setuptools import setup, find_namespace_packages
 from pathlib import Path
 
 # Read the contents of our README file for PyPi
@@ -9,7 +9,7 @@
 
 setup(
     name = 'OpenFisca-France',
-    version = '148.0.0',
+    version = '149.0.0',
     author = 'OpenFisca Team',
     author_email = 'contact@openfisca.fr',
     classifiers = [
@@ -17,10 +17,9 @@
         'License :: OSI Approved :: GNU Affero General Public License v3',
         'Operating System :: POSIX',
         'Programming Language :: Python',
-        'Programming Language :: Python :: 3.6',
-        'Programming Language :: Python :: 3.7',
-        'Programming Language :: Python :: 3.8',
         'Programming Language :: Python :: 3.9',
+        'Programming Language :: Python :: 3.10',
+        'Programming Language :: Python :: 3.11',
         'Topic :: Scientific/Engineering :: Information Analysis',
         ],
     description = 'French tax and benefit system for OpenFisca',
@@ -39,37 +38,37 @@
         ],
     extras_require = {
         'inversion_revenus': [
-            'scipy >= 0.17',
+            'scipy >=1.10.1, <2.0',
             ],
         'de_net_a_brut': [
-            'scipy >= 0.17',
+            'scipy >=1.10.1, <2.0',
             ],
         'taxipp': [
-            'pandas >= 0.13',
+            'pandas >=1.5.3, <2.0',
             ],
         'dev': [
-            'autopep8 ==1.5.7',
-            'flake8 >= 4.0.0, < 5.0.0',
-            'flake8-print >= 5.0.0, < 6.0.0',
-            'flake8-quotes >= 3.3.1, < 6.0.0',
-            'pytest >= 5.0.0, < 7.0.0',
-            'scipy >= 0.17',  # Only used to test de_net_a_brut reform
-            'requests >= 2.8',
-            'yamllint >=1.11.1,<1.27'
+            'autopep8 >=2.0.2, <3.0',
+            'flake8 >=6.0.0, <7.0.0',
+            'flake8-print >=5.0.0, <6.0.0',
+            'flake8-quotes >=3.3.2',
+            'pytest >=7.2.2, <8.0',
+            'scipy >=1.10.1, <2.0',  # Only used to test de_net_a_brut reform
+            'requests >=2.28.2, <3.0',
+            'yamllint >=1.30.0, <2.0'
             ],
         'casd-dev': [
             # Same as dev with packages not available at CASD removed
-            'autopep8 >=1.3.2',
-            'pytest >= 5.0.0, < 7.0.0',
-            'requests >= 2.8',
-            'scipy >= 0.17',  # Only used to test de_net_a_brut reform
+            'autopep8 >=2.0.2, <3.0',
+            'pytest >=7.2.2, <8.0',
+            'requests >=2.28.2, <3.0',
+            'scipy >=1.10.1, <2.0',  # Only used to test de_net_a_brut reform
             ]
         },
     include_package_data = True,  # Will read MANIFEST.in
     install_requires = [
-        'OpenFisca-Core >=35.8.0,<36.0',
+        'OpenFisca-Core >=40, <41',
         ],
-    packages = find_packages(exclude = [
+    packages = find_namespace_packages(exclude = [
         'openfisca_france.tests*',
         'openfisca_france.assets.taxe_habitation.source*',
         ]),
diff --git a/tests/formulas/age.yaml b/tests/formulas/age.yaml
index 2afb21337f..336934d64d 100644
--- a/tests/formulas/age.yaml
+++ b/tests/formulas/age.yaml
@@ -116,3 +116,24 @@
       - 40
       - 9
       - 9
+- name: Age des enfants dans les familles sans enfants (pour éviter les -inf)
+  period: 2015-01
+  absolute_error_margin: 0.005
+  input:
+    famille:
+      parents: [parent1, parent2]
+    foyer_fiscal:
+      declarants: [parent1, parent2]
+    menage:
+      personne_de_reference: parent1
+      conjoint: parent2
+    individus:
+      parent1:
+        age_en_mois:
+          2015-01: 40 * 12
+      parent2:
+        age_en_mois:
+          2015-01: 40 * 12
+  output:
+    af_age_aine:
+      2015-01: -9999
diff --git a/tests/test_entities.py b/tests/test_entities.py
index 8cedba7b84..adb6e6a0db 100644
--- a/tests/test_entities.py
+++ b/tests/test_entities.py
@@ -112,7 +112,7 @@ def test_transpose_string():
 
     depcom_famille = famille.first_person.menage('depcom', period = reference_period)
 
-    assert((depcom_famille == [b'93400', b'89300']).all())
+    assert (depcom_famille == [b'93400', b'89300']).all()
 
 
 def test_value_from_person():