- HMRC is consulting on modernising and standardising the format of UK corporation tax (CT) computations.
- The consultation aims to address the current inconsistency and divergence in free-format submissions, despite existing XBRL tagging.
- HMRC proposes a new prescribed "standardised, fully tagged format" to enhance the quality and consistency of CT data received. It also proposes measures to ensure the new format is used correctly once mandated, such as regular reviews of approved software, blocking non-compliant tools, and penalties for non-compliant software providers.
- Separately, HMRC intends to mandate online filing for all amended CT returns.
- Timing: the consultation closes on 2 June 2026. The implementation plan includes a collaborative development phase (April-September 2026), a software build period (October 2026-September 2027), and an initial pilot (October 2027-September 2028). The online filing mandate for all amended CT returns is proposed to commence from 1 April 2027.
Resources (click to open)
- HMRC launches consultation on the format of corporation tax computations (Deloitte tax@hand, March 2026)
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