Look a company up on the register, or type its year end, and see when its accounts, Corporation Tax and Company Tax Return are due, with the days left for each. Nothing is saved, and you don't need an account.
Accounts due at Companies House
31 Dec 2026
9 months after the year end
Accounts9 months after the year end
…
31 Dec 2026
Corporation Tax payment9 months and 1 day after the period ends
…
1 Jan 2027
Company Tax Return (CT600)12 months after the period ends
Accounts: 9 months after the end of the accounting period. A first period of more than 12 months is due 21 months after incorporation, or 3 months after its end if that is later1.
Corporation Tax: paid 9 months and 1 day after the end of each Corporation Tax accounting period, for profits up to £1.5 million2. The Company Tax Return is due 12 months after the period ends3. An accounting period is never more than 12 months, so a long first period has two of each4.
Looking a company up uses the dates on the Companies House register, with the same rules for tax.
File for your company
Search the Companies House register. Your company page shows every date that applies to it, and what to file next.
Questions
When are a company’s first accounts due?
Usually 21 months after the company was incorporated, when its first period runs over 12 months, or 3 months after that period ends if that is later.
Can I get an extension?
Only for an event outside your control, such as an unexpected illness, and you must apply to Companies House before the deadline. HMRC’s dates don’t move.
Why are there two Corporation Tax dates for my first year?
A Corporation Tax accounting period is never more than 12 months. A first period of accounts that runs longer is split in two, and each part has its own payment date and its own return.
How we wrote this. Drafted with AI assistance from the sources above. Every fact was then checked against GOV.UK, legislation.gov.uk and HMRC’s manuals, last on 24 October 2026. It is general information, not advice on your own situation. Editorial policy