Form detail
HMRC Form CT600
Company Tax Return
Country
United Kingdom
Revision year
2024
Methods
efile
Updated
2026-05-20
Company Tax Return
Annual corporation tax return for UK companies and certain non-UK companies trading in the UK.
Who must file: UK-resident companies and non-UK companies with a UK permanent establishment or UK-source income subject to corporation tax.
Practical overview
CT600 must be filed online via HMRC and is paired with iXBRL-tagged statutory accounts and computations. The filing deadline is 12 months after the accounting period end, but payment is due 9 months and 1 day after the period end (or quarterly for large companies). The main corporation tax rate is 25 percent for profits above 250,000 GBP with the small-profits rate of 19 percent for profits below 50,000 GBP and marginal relief in between.
Practical steps
- Prepare statutory accounts and corporation tax computations.
- Tag accounts and computations in iXBRL format.
- File CT600 with accounts and computations via HMRC online services.
- Pay corporation tax 9 months and 1 day after period end (or quarterly for large companies).
Due-date notes
Filing: 12 months after accounting period end. Payment: 9 months and 1 day after period end.
Timing: 12 months after period end
Penalty snapshot
100 GBP automatic penalty for late filing, escalating penalties for continued lateness, and interest on unpaid corporation tax.
Related guides
Primary sources
- HMRC: CT600 publicationVerified 2026-05-20
Important disclaimer
This library is for general tax education only. Always verify filing obligations, due dates, and tax consequences against the cited primary source or with a qualified tax professional.