HMRC Self Assessment API

The HMRC Self Assessment APIs enable software to submit and manage self assessment tax returns, income sources, and tax calculations for individuals and sole traders under Making Tax Digital for Income Tax.

Work with this as data

Every API here is available over the APIs.io API and to AI agents over MCP.

MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

https://apis.io/mcp

Tools for apis

7 MCP tools reach this
  • find_apisBrowse and filter every API in the catalog.
  • get_api_artifactsOne API's artifacts, grouped by type.
  • get_openapiThe primary OpenAPI for this API.
  • find_similar_apisAPIs that look like this one.
  • apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
  • resolveTurn a domain, URL or GitHub org into the provider it belongs to.
  • find_cohortsEvery scored population of providers in the catalog.
All 92 tools →

Call it yourself

curl for this page
This API
curl "https://apis.io/api/v1/apis/hmrc-self-assessment-api"
All apis
curl "https://apis.io/api/v1/apis?limit=25"

Discovery needs no key. Ratings and market analysis are Pro.

Get an API key

Free tier, no form to fill in. Signing in shares your email address with us — we store it to create your key and to recognise you if you sign in with another provider. See our Privacy Policy and Terms.

A second provider on the same verified email joins the account you already have.

API entry from apis.yml

apis.yml Raw ↑
aid: hmrc:hmrc-self-assessment-api
name: HMRC Self Assessment API
description: The HMRC Self Assessment APIs enable software to submit and manage self assessment tax returns,
  income sources, and tax calculations for individuals and sole traders under Making Tax Digital for Income
  Tax.
humanURL: https://developer.service.hmrc.gov.uk/api-documentation/docs/api
baseURL: https://api.service.hmrc.gov.uk
tags:
- Government
- Income Tax
- REST
- Self Assessment
- Tax
- UK
properties:
- type: Documentation
  url: https://developer.service.hmrc.gov.uk/api-documentation/docs/api
- type: Authentication
  url: https://developer.service.hmrc.gov.uk/api-documentation/docs/authorisation