diff --git a/packages/dnb-design-system-portal/src/docs/uilib/extensions/forms/feature-fields/NationalIdentityNumber/info.mdx b/packages/dnb-design-system-portal/src/docs/uilib/extensions/forms/feature-fields/NationalIdentityNumber/info.mdx
index 47a38d732c4..d6200d9feef 100644
--- a/packages/dnb-design-system-portal/src/docs/uilib/extensions/forms/feature-fields/NationalIdentityNumber/info.mdx
+++ b/packages/dnb-design-system-portal/src/docs/uilib/extensions/forms/feature-fields/NationalIdentityNumber/info.mdx
@@ -10,6 +10,7 @@ This field is meant for [Norwegian national identity numbers(fnr)](https://www.s
 More info can be found at [Skatteetaten](https://www.skatteetaten.no/en/person/national-registry/identitetsnummer/fodselsnummer/#:~:text=A%20national%20identity%20number%20consists,national%20identity%20number%20are%20220676)
 
 It validates input for [Norwegian national identity numbers(fnr)](https://www.skatteetaten.no/en/person/national-registry/identitetsnummer/fodselsnummer/) and [D numbers](https://www.skatteetaten.no/en/person/national-registry/identitetsnummer/d-nummer/) using the [fnrvalidator](https://github.com/navikt/fnrvalidator).
+The validation happens on blur, internally using the `onBlurValidator` [property](/uilib/extensions/forms/feature-fields/NationalIdentityNumber/properties/#field-specific-properties).
 
 ```jsx
 import { Field } from '@dnb/eufemia/extensions/forms'
diff --git a/packages/dnb-eufemia/src/extensions/forms/Field/NationalIdentityNumber/NationalIdentityNumberDocs.tsx b/packages/dnb-eufemia/src/extensions/forms/Field/NationalIdentityNumber/NationalIdentityNumberDocs.tsx
index 2445ff8175b..bb3c6a6c059 100644
--- a/packages/dnb-eufemia/src/extensions/forms/Field/NationalIdentityNumber/NationalIdentityNumberDocs.tsx
+++ b/packages/dnb-eufemia/src/extensions/forms/Field/NationalIdentityNumber/NationalIdentityNumberDocs.tsx
@@ -11,4 +11,9 @@ export const NationalIdentityNumberProperties: PropertiesTableProps = {
     type: 'object',
     status: 'optional',
   },
+  onBlurValidator: {
+    doc: 'Custom validator function that is triggered when the user leaves a field (e.g., blurring a text input or closing a dropdown). The function can be either asynchronous or synchronous. The first parameter is the value, and the second parameter returns an object containing { errorMessages, connectWithPath, validators }. Defaults to validation of the identification number(national identity numbers and D numbers).',
+    type: 'function',
+    status: 'optional',
+  },
 }