Other Deductions (MTD) API

	REST
	Version 2.0 - beta
	06 May 2026
Sandbox base URL	https://test-api.service.hmrc.gov.uk
Production base URL	https://api.service.hmrc.gov.uk

Overview

Use the Other Deductions API to submit, edit and retrieve information about a customer’s Seafarers’ Earnings Deductions.

This API is related to the following customer journey:

• Submit seafarers deductions

Some parameters in this API map to box numbers in one or more Self Assessment tax return forms. To learn more and to download this mapping information as a CSV file, go to income-tax-mtd-changelog/mapping-csv-files.md on GitHub. For information on how to connect to this API see the Income Tax MTD end-to-end service guide.

Errors

Errors returned by this API are listed in the Response section of each endpoint. Read the reference guide for more information about errors.

Testing

You can use the Sandbox environment to test this API. You can test different scenarios in the Sandbox by passing the Gov-Test-Scenario header. The Sandbox also allows you to perform stateful and dynamic testing for some APIs. The ‘Test data’ section under each endpoint explains the test scenarios that can be simulated.

If you have a specific testing need that is not supported in the Sandbox, contact our Software Developers Support Team. Some endpoints may be marked ‘[test only]’, which means that they are not available for use in Production and may change.

Fraud Prevention

HMRC monitors transactions to help protect your customers' confidential data from criminals and fraudsters.

Warning You are required by law to submit header data for this API. This includes all associated APIs and endpoints.

Check the data you need to send. You can also use the Test API during initial development and as part of your quality assurance checks.

Versioning

When backwards-incompatible changes are made to this API, we release a new version. Read the reference guide for more information about API versioning. For updates about all our APIs, refer to the API changelog.

Endpoints

Version	Environments	Endpoints
Version 2.0 - beta (opens in new tab)	Sandbox and Production	2.0 endpoints

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