diff --git a/examples/data/ldcE.ts b/examples/data/ldcE.ts
index 20319dde..6d661ccd 100644
--- a/examples/data/ldcE.ts
+++ b/examples/data/ldcE.ts
@@ -1234,7 +1234,7 @@ export const validLDCE: Schema = {
       flowId: '824628b2-deeb-48b0-92b1-2ca7f3b17163',
       url: 'https://www.editor.planx.dev/buckinghamshire/apply-for-a-lawful-development-certificate/preview',
     },
-    submittedAt: '2023-10-02 00:00:00',
+    submittedAt: '2023-10-02t00:00:00z',
     schema:
       'https://theopensystemslab.github.io/digital-planning-data-schemas/@next/schema.json',
   },
diff --git a/examples/data/ldcP.ts b/examples/data/ldcP.ts
index 500b8f76..47fdac6b 100644
--- a/examples/data/ldcP.ts
+++ b/examples/data/ldcP.ts
@@ -838,7 +838,7 @@ export const validLDCP: Schema = {
       flowId: '824628b2-deeb-48b0-92b1-2ca7f3b17163',
       url: 'https://www.editor.planx.dev/buckinghamshire/apply-for-a-lawful-development-certificate/preview',
     },
-    submittedAt: '2023-10-02 00:00:00',
+    submittedAt: '2023-10-02T00:00:00+01:00',
     schema:
       'https://theopensystemslab.github.io/digital-planning-data-schemas/@next/schema.json',
   },
diff --git a/examples/data/planningPermission.ts b/examples/data/planningPermission.ts
index 46c73920..20c0c1b1 100644
--- a/examples/data/planningPermission.ts
+++ b/examples/data/planningPermission.ts
@@ -1256,7 +1256,7 @@ export const validPlanningPermission: Schema = {
       flowId: '01e38c5d-e701-4e44-acdc-4d6b5cc3b854',
       url: 'https://www.editor.planx.dev/lambeth/apply-for-planning-permission/preview',
     },
-    submittedAt: '2023-10-02 00:00:00',
+    submittedAt: '2023-10-02T00:00:00.00Z',
     schema:
       'https://theopensystemslab.github.io/digital-planning-data-schemas/@next/schema.json',
   },
diff --git a/examples/data/priorApproval.ts b/examples/data/priorApproval.ts
index 406b6632..9254a72a 100644
--- a/examples/data/priorApproval.ts
+++ b/examples/data/priorApproval.ts
@@ -774,7 +774,7 @@ export const validPriorApproval: Schema = {
       flowId: 'c6628103-c648-4663-81e1-bfa0a1a18340',
       url: 'https://www.editor.planx.dev/southwark/apply-for-prior-approval/preview',
     },
-    submittedAt: '2023-10-02 00:00:00',
+    submittedAt: '2023-10-02T00:00:00Z',
     schema:
       'https://theopensystemslab.github.io/digital-planning-data-schemas/@next/schema.json',
   },
diff --git a/schema/schema.json b/schema/schema.json
index 5896dcb4..b2fa8876 100644
--- a/schema/schema.json
+++ b/schema/schema.json
@@ -1227,7 +1227,9 @@
       "type": "string"
     },
     "DateTime": {
+      "description": "Regex-based implementation of iso-date-time until available in ajv-formats@3.0.0",
       "format": "date-time",
+      "pattern": "^([0-9]+)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])[Tt]([01][0-9]|2[0-3]):([0-5][0-9]):([0-5][0-9]|60)(\\.[0-9]+)?(([Zz])|([\\+|\\-]([01][0-9]|2[0-3]):[0-5][0-9]))$",
       "type": "string"
     },
     "Email": {
diff --git a/types/utils.ts b/types/utils.ts
index 07574b8a..946b0443 100644
--- a/types/utils.ts
+++ b/types/utils.ts
@@ -18,6 +18,8 @@ export type URL = string;
 
 /**
  * @format date-time
+ * @pattern ^([0-9]+)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])[Tt]([01][0-9]|2[0-3]):([0-5][0-9]):([0-5][0-9]|60)(\.[0-9]+)?(([Zz])|([\+|\-]([01][0-9]|2[0-3]):[0-5][0-9]))$
+ * @description Regex-based implementation of iso-date-time until available in ajv-formats@3.0.0
  */
 export type DateTime = string;