Self Assessment generic technical specifications (2015)

Returns technical specifications for Self Assessment Online software developers.


Transaction Engine: Support for software developers

HMRC(IR)mark: support for software developers

Attachment recognition version 1.0 (9 February 2015)

This file may not be suitable for users of assistive technology. Request an accessible format.

If you use assistive technology (such as a screen reader) and need a version of this document in a more accessible format, please email Please tell us what format you need. It will help us if you say what assistive technology you use.


Returns technical specifications for software developers working with the Self Assessment Online service.

Published 20 January 2015
Last updated 12 February 2015 + show all updates
  1. Attachment recognition version 1.0 (9 February 2015) ZIP added.
  2. First published.