This version is in beta - expect some breaking changes.

National Insurance API

Version and status
Available in Sandbox Yes
Sandbox base URL
Available in Production Yes
Production base URL


This API retrieves an annual summary of an individual taxpayer's class 1 total earnings and class 2 National Insurance contributions due for a given tax year.

Its primary use is for the calculation of a self-employed taxpayer's National Insurance liability within the Self Assessment tax calculation.



You can use the sandbox environment to test this API.

It supports stateful behaviour. You can set up test data for this API using the National Insurance Test Support API.



View API endpoints
Why do these endpoints look different?

The endpoints for this API now use the Open API Specification (OAS).

The API has not changed. You do not need to make any updates to your application if you already use this API.