Fill the CT600 Form Online — Free, No Software Download

The CT600 is the HMRC Company Tax Return — the official form a UK limited company uses to report its taxable profits and calculate Corporation Tax for an accounting period. The current version is the CT600 (2024) Version 3, used for accounting periods starting on or after 1 April 2015. A complete Company Tax Return is the CT600 itself, plus iXBRL-tagged statutory accounts, tax computations, and any supplementary pages that apply (CT600A through CT600M).

Every active UK limited company must file a CT600 with HMRC — including private limited companies, public limited companies, and unincorporated associations within the charge to Corporation Tax. Sole traders and ordinary partnerships do not file CT600s (they file Self Assessment instead). HMRC will normally issue a 'notice to deliver a Company Tax Return' (form CT603) at the end of each accounting period, and you must respond by filing a CT600 even if no tax is due.

The CT600 must be filed with HMRC within 12 months after the end of your company's accounting period. Note that the Corporation Tax payment deadline is earlier — 9 months and 1 day after the end of the accounting period for most small and medium companies. So you usually pay the tax before you file the return. A late CT600 triggers automatic penalties: £100 if it is up to 3 months late, another £100 at 3 months, plus 10% of unpaid tax at 18 months and a further 10% at 24 months.

Supplementary pages are added to the main CT600 when specific circumstances apply. The main ones are: CT600A (close company loans to participators), CT600B (controlled foreign companies and bank levy), CT600C (group and consortium relief), CT600D (insurance), CT600E (charities and Community Amateur Sports Clubs), CT600F (tonnage tax), CT600H (cross-border royalties), CT600I (supplementary charge in respect of ring fence trades), CT600J (disclosure of tax avoidance schemes, DOTAS), CT600K (restitution tax), CT600L (research and development), CT600M (freeports and investment zones) and CT600N (residential property developer tax). You only attach the pages that apply to your company.

Yes. Companies must submit their statutory accounts and Corporation Tax computations to HMRC in iXBRL (Inline eXtensible Business Reporting Language) format alongside the CT600. iXBRL adds machine-readable tags to a normal PDF or HTML accounts document. Most commercial CT software and HMRC's online Company Tax Return service produce iXBRL output automatically. The PDF CT600 from gov.uk that you fill in PDF Edit is the cover form — when you submit officially through HMRC, the iXBRL accounts and computations travel with it as separate attachments.

HMRC withdrew the CT600 (Short) in April 2015. Since then, all companies use the same full CT600 (2024) Version 3, regardless of size. The current CT600 is around 11 pages and is designed to handle both small and large companies — sections that do not apply to your company are simply left blank. If you see references to the 'CT600 Short' or 'CT600 Full' in older guides, they relate to accounting periods before 1 April 2015.

Research and development claims are made on supplementary page CT600L, alongside the main CT600 and a mandatory Additional Information Form (AIF) submitted before or with the return. CT600L captures the SME R&D scheme amount, the Research & Development Expenditure Credit (RDEC), and the merged R&D scheme that applies to accounting periods beginning on or after 1 April 2024. From August 2023 onwards HMRC requires the AIF for every R&D claim — without it, the claim is invalid and HMRC will reject the relief.

Each company in a group files its own CT600. Group relief — the surrender of losses between members of a 75% group — is claimed on supplementary page CT600C, supported by a notice of consent from the surrendering company. Worldwide groups within the corporate interest restriction or with controlled foreign company exposure use CT600B. There is no consolidated UK Corporation Tax return; the parent does not file on behalf of the subsidiaries.

Only if HMRC has issued a notice to deliver a Company Tax Return (CT603). If your company is dormant for Corporation Tax and you have told HMRC, they may agree that no CT600 is needed for that period. If you have received a CT603, you must still file a CT600 — even with all-zero figures — to avoid late filing penalties. Note that 'dormant for Corporation Tax' (HMRC) and 'dormant for Companies House' (no significant accounting transactions) are separate concepts with separate rules.

No. Official CT600 submission to HMRC must go through the online Company Tax Return service on gov.uk or through commercial CT software that produces iXBRL accounts and computations. PDF Edit lets you open the official HMRC PDF, fill it in cleanly in your browser, and save or print a copy for your records, your accountant, or as a working draft before you submit the figures online. Nothing you type leaves your device — PDF Edit processes the form locally, with no account required.