- HMRC held a consultation on modernising and standardising the format of UK corporation tax (CT) computations.
- The consultation aimed to address the current inconsistency and divergence in free-format submissions, despite existing XBRL tagging.
- HMRC proposed a new prescribed "standardised, fully tagged format" to enhance the quality and consistency of CT data received. They also proposed 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 intend to mandate online filing for all amended CT returns.
- Timing: the consultation closed on 2 June 2026. The consultation document explored delivery timescales and invited feedback on a proposed implementation plan that included a collaborative development phase (April-September 2026), a software build period (October 2026-September 2027), and an initial pilot (October 2027-September 2028). The consultation document also proposed that the online filing mandate for all amended CT returns should commence from 1 April 2027.
Resources (click to open)
- HMRC launches consultation on the format of corporation tax computations (Deloitte tax@hand, March 2026)
- Modernising and standardising company tax returns (HMRC, consultation, March 2026)
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