When Are My Limited Company Accounts and Corporation Tax Due in 2026/27?
If you run a private limited company, there are three deadlines to remember. Your annual accounts are due at Companies House 9 months after your company’s financial year ends. Your Corporation Tax bill must be paid 9 months and 1 day after the end of your accounting period. And your Company Tax Return (CT600) must reach HMRC 12 months after the end of that accounting period. Miss any of them and automatic penalties start immediately – here is how the 2026/27 deadlines work in practice.
The three deadlines every director needs to know
It surprises many small-company owners that limited company compliance is split between two different bodies, each with its own clock:
- Annual accounts – Companies House: due 9 months after your financial year end. A company with a 31 March year end must file by 31 December the same year.
- Corporation Tax payment – HMRC: due 9 months and 1 day after the end of your Corporation Tax accounting period. Note the odd order: you must pay the tax before the return itself is due.
- Company Tax Return (CT600) – HMRC: due 12 months after the end of the accounting period, filed together with your full accounts and tax computations.
In practice, most small companies deal with everything in one sitting: prepare the accounts, work out the Corporation Tax, file both returns and pay HMRC well before the nine-month mark. That approach also tells you your tax bill months in advance, which makes cash-flow planning far easier. Our accounts and Corporation Tax return service handles the whole cycle for a fixed fee.
Different rules for your first year
A brand-new company gets slightly different deadlines. Your first set of accounts is due 21 months after the date you registered with Companies House, because your first financial year usually runs a little longer than 12 months. For the same reason, HMRC often splits your first period into two accounting periods for Corporation Tax, each with its own payment date and return – a common trap for first-time directors.
What Corporation Tax will you pay in 2026/27?
For the financial year beginning 1 April 2026, the rates are unchanged:
- Small profits rate: 19% – profits of £50,000 or less.
- Main rate: 25% – profits above £250,000.
- Marginal relief – profits between £50,000 and £250,000 pay 25% less marginal relief, calculated with the standard fraction of 3/200. The effective rate slides from 19% up towards 25% as profits rise.
The £50,000 and £250,000 limits are reduced proportionately if your accounting period is shorter than 12 months or if you have associated companies – two companies under common control share one set of limits between them.
Worked example: £80,000 profit, 31 March 2027 year end
Suppose your company makes £80,000 of taxable profit in the year to 31 March 2027, with no associated companies.
- Tax at the main rate: £80,000 × 25% = £20,000
- Marginal relief: 3/200 × (£250,000 − £80,000) = 3/200 × £170,000 = £2,550
- Corporation Tax due: £20,000 − £2,550 = £17,450 – an effective rate of about 21.8%
And the diary dates that follow from that year end:
- 31 December 2027 – accounts due at Companies House
- 1 January 2028 – £17,450 Corporation Tax payable to HMRC
- 31 March 2028 – CT600 due at HMRC
You can test your own numbers in seconds with our free Corporation Tax calculator, and see every filing date for the year in our UK tax deadlines calendar.
What happens if you miss a deadline?
Penalties are automatic – there is no warning letter first.
Late accounts at Companies House
- Up to 1 month late: £150
- 1 to 3 months late: £375
- 3 to 6 months late: £750
- More than 6 months late: £1,500
These penalties are doubled if your accounts are late two years in a row, and persistent non-filing can ultimately lead to the company being struck off.
Late Company Tax Return at HMRC
Filing the CT600 even one day late triggers a £200 penalty, with another £200 at three months. At six months HMRC estimates your bill and adds 10% of the unpaid tax, and another 10% at twelve months. File late three times in a row and the fixed penalties rise to £1,000 each. Interest also runs on Corporation Tax paid after the due date.
The full rules are set out in HMRC’s guidance on accounts and tax returns for private limited companies on GOV.UK.
How to stay ahead of the deadlines
The simplest protection is to get your accounts prepared within two or three months of your year end, not the week before the deadline. You will know your Corporation Tax bill nine or ten months before it is payable, you leave room to claim reliefs properly, and there is time to fix queries without panic. If your bookkeeping is tidy through the year – or handled by us alongside your accounts – year end becomes a formality rather than a scramble.
Frequently asked questions
Can I file my accounts and Company Tax Return at the same time?
Yes. Most small companies file their Companies House accounts and their HMRC Company Tax Return together, well before the nine-month accounts deadline. Doing both at once means one set of figures, one sign-off and no risk of the two filings drifting apart.
Do I still need to file if my company made no profit or did not trade?
Yes. A loss-making company must still file accounts and a CT600. A genuinely dormant company must still file (simpler) dormant accounts at Companies House and should tell HMRC it is dormant so Corporation Tax return notices stop being issued.
Can I change my company’s year end to buy more time?
You can shorten your accounting reference date as often as you like, and lengthen it (generally to a maximum of 18 months) once every five years, which can change your filing deadline. It is a useful planning tool, but it needs care – take advice before relying on it to escape an imminent deadline.
Written by the Accountactical Team — ACCA-Approved Accountants, London.
This article is general information for UK small-business owners, not formal tax advice – speak to an accountant about your own circumstances before acting on it.
