National Insurance API
| REST | |
| Version 1.1 - beta | |
| 05 May 2026 | |
| Sandbox base URL | https://test-api.service.hmrc.gov.uk |
| Production base URL | https://api.service.hmrc.gov.uk |
Overview
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.
Errors
We use standard HTTP status codes to show whether an API request succeeded or not. They are usually in the range:
- 200 to 299 if it succeeded, including code 202 if it was accepted by an API that needs to wait for further action
- 400 to 499 if it failed because of a client error by your application
- 500 to 599 if it failed because of an error on our server
Errors specific to each API are shown in the Endpoints section, under Response. See our reference guide for more on errors.
Testing
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.
Versioning
When an API changes in a way that is backwards-incompatible, we increase the version number of the API. See our reference guide for more on versioning.
Endpoints
| Version | Environments | Endpoints |
|---|---|---|
|
Version 1.1 - beta
(opens in new tab) |
Sandbox and Production | 1.1 endpoints |