Corporation Tax deadlines for limited companies

Take a company with a 31 March 2026 year end as a worked example:

• 31 December 2026 — statutory accounts due at Companies House (9 months after year end)
• 1 January 2027 — Corporation Tax payment due to HMRC (9 months and 1 day after the period ends)
• 31 March 2027 — CT600 Company Tax Return due to HMRC (12 months after the period ends)

The payment date landing before the return date trips up new directors every year. The practical answer: prepare everything within a few months of year end, so the tax bill is known long before it’s due.

• 1 day late: £100
• 3 months late: a further £100
• 6 months late: HMRC estimates your bill and adds a penalty of 10% of the unpaid tax
• 12 months late: a further 10% of any unpaid tax

File late three accounting periods in a row and the £100 penalties rise to £500 each. Late payment doesn’t attract those fixed penalties but interest runs daily on the unpaid amount — and remember Companies House charges its own separate penalties if the accounts are late too.

Companies House penalties explained →

A Company Tax Return can cover at most 12 months, but a new company’s first accounting period is usually slightly longer (incorporation date to the end of the month a year later). Result: the first year often needs two CT600s — one for the first 12 months and one for the stub period — each with its own payment date. It’s routine for an accountant, and a common shock for DIY filers.

Pay electronically using your 17-character Corporation Tax payment reference (it changes each period — using last year’s reference misallocates the payment). Faster Payments and online banking clear same or next day; Direct Debit takes longer to set up the first time. HMRC does not accept personal credit cards.

Want the whole cycle handled — accounts, computation, return and payment reminders? Call 0114 327 1480.

Our Corporation Tax return service →