diff --git a/backend/benefit/applications/api/v1/serializers/application.py b/backend/benefit/applications/api/v1/serializers/application.py
index ba04c748d7..7a536201c1 100755
--- a/backend/benefit/applications/api/v1/serializers/application.py
+++ b/backend/benefit/applications/api/v1/serializers/application.py
@@ -1472,15 +1472,10 @@ class ApplicantApplicationSerializer(BaseApplicationSerializer):
         ),
     )
 
-    batch = SimpleApplicationBatchSerializer(
-        allow_null=True,
-        required=False,
-    )
+    has_batch = serializers.SerializerMethodField()
 
-    def get_batch(self, _):
-        if self.batch:
-            return True
-        return None
+    def get_has_batch(self, obj):
+        return obj.batch is not None
 
     changes = serializers.SerializerMethodField(
         help_text=("Possible changes made by handler to the application."),
@@ -1510,7 +1505,7 @@ def update(self, instance, validated_data):
         return self._base_update(instance, validated_data)
 
     class Meta(BaseApplicationSerializer.Meta):
-        fields = BaseApplicationSerializer.Meta.fields + ["batch"]
+        fields = BaseApplicationSerializer.Meta.fields + ["batch", "has_batch"]
 
 
 class HandlerApplicationSerializer(BaseApplicationSerializer):
diff --git a/backend/benefit/applications/tests/test_applications_api.py b/backend/benefit/applications/tests/test_applications_api.py
index 255b93dec6..102a8b24bf 100755
--- a/backend/benefit/applications/tests/test_applications_api.py
+++ b/backend/benefit/applications/tests/test_applications_api.py
@@ -3,6 +3,7 @@
 import os
 import re
 import tempfile
+import uuid
 from datetime import date, datetime, timedelta, timezone
 from decimal import Decimal
 from unittest import mock
@@ -376,7 +377,7 @@ def test_application_single_read_without_ahjo_decision_as_applicant(
     assert response.data["ahjo_decision"] is None
     assert response.data["application_number"] is not None
     assert response.data["status"] == visible_status
-    assert response.data["batch"] is None
+    assert response.data["has_batch"] is False
     assert Decimal(response.data["duration_in_months_rounded"]) == duration_in_months(
         application.start_date, application.end_date, decimal_places=2
     )
@@ -387,7 +388,8 @@ def test_application_single_read_without_ahjo_decision_as_applicant(
     response = api_client.get(get_detail_url(application))
 
     assert response.status_code == 200
-    assert response.data["batch"] is True
+    assert response.data["has_batch"] is True
+    assert isinstance(response.data["batch"], uuid.UUID)
 
 
 @pytest.mark.parametrize(
@@ -410,7 +412,9 @@ def test_application_single_read_with_ahjo_decision_as_applicant(
     assert response.data["ahjo_decision"] is not None
     assert response.data["application_number"] is not None
     assert response.data["status"] == visible_status
-    assert response.data["batch"] is True
+    assert response.data["has_batch"] is True
+
+    assert isinstance(response.data["batch"], uuid.UUID)
     assert Decimal(response.data["duration_in_months_rounded"]) == duration_in_months(
         application.start_date, application.end_date, decimal_places=2
     )
diff --git a/frontend/benefit/applicant/src/components/header/useHeader.ts b/frontend/benefit/applicant/src/components/header/useHeader.ts
index a6625238f0..cdf23d4354 100644
--- a/frontend/benefit/applicant/src/components/header/useHeader.ts
+++ b/frontend/benefit/applicant/src/components/header/useHeader.ts
@@ -50,7 +50,7 @@ const useHeader = (): ExtendedComponentProps => {
   );
 
   const { data: application } = useApplicationQuery(id);
-  const canWriteNewMessages = !application?.batch;
+  const canWriteNewMessages = !application?.has_batch;
 
   useEffect(() => {
     if (application?.unread_messages_count) {
diff --git a/frontend/benefit/shared/src/types/application.d.ts b/frontend/benefit/shared/src/types/application.d.ts
index 369e8af630..9d937f3bbd 100644
--- a/frontend/benefit/shared/src/types/application.d.ts
+++ b/frontend/benefit/shared/src/types/application.d.ts
@@ -441,6 +441,7 @@ export type ApplicationData = {
   training_compensations: TrainingCompensationData[];
   handled_at?: string;
   batch?: BatchData;
+  has_batch?: boolean;
   latest_decision_comment?: string;
   unread_messages_count?: number;
   application_origin?: APPLICATION_ORIGINS;