Key takeaways
- Most companies pay Corporation Tax 9 months and 1 day after the end of their accounting period.
- Companies with profits over £1.5 million pay in quarterly instalments, starting during the accounting period itself.
- The payment deadline comes three months before the 12-month deadline for filing the CT600.
- Late payment interest runs from the due date at the Bank of England base rate plus 4%.
- You need the company's 17-character payment reference, based on its UTR, to pay correctly.
Corporation Tax works on the company’s own accounting periods rather than the tax year, so every company has its own payment dates. Missing them brings interest, and for large companies the instalment rules mean tax is due before the year has even ended.
The normal deadline: 9 months and 1 day
If your company’s taxable profits are £1.5 million or less (divided between associated companies), Corporation Tax is due 9 months and 1 day after the end of the accounting period.
| Accounting period ends | Corporation Tax due | CT600 due |
|---|---|---|
| 31 March 2026 | 1 January 2027 | 31 March 2027 |
| 30 June 2026 | 1 April 2027 | 30 June 2027 |
| 30 September 2026 | 1 July 2027 | 30 September 2027 |
| 31 December 2026 | 1 October 2027 | 31 December 2027 |
HMRC does not send a bill. You work out the tax in the company’s return and pay by the due date, even if you have not filed yet.
Large and very large companies
| Company size (taxable profits) | When tax is paid |
|---|---|
| Up to £1.5 million | One payment, 9 months and 1 day after the period ends |
| Over £1.5 million (“large”) | Four quarterly instalments in months 7, 10, 13 and 16 of a 12-month period |
| Over £20 million (“very large”) | Four quarterly instalments in months 3, 6, 9 and 12 of the period |
A company is not treated as large in its first year of being large if its profits are no more than £10 million and it was not large in the previous 12 months. The thresholds are divided by the number of associated companies plus one. See Corporation Tax instalments.
Accounting periods and the first year
An accounting period for Corporation Tax cannot be longer than 12 months. If a company’s accounts cover a longer period, typically its first period after incorporation, there are two accounting periods: the first 12 months and the remainder, each with its own payment date and return.
Example
A company incorporated on 1 February 2025 prepares its first accounts to 31 March 2026, a 14-month period.
| Accounting period | Tax due | CT600 due |
|---|---|---|
| 1 February 2025 to 31 January 2026 | 1 November 2026 | 31 March 2027 |
| 1 February 2026 to 31 March 2026 | 1 January 2027 | 31 March 2027 |
Both returns are due 12 months after the end of the period of account (the accounts year end), but the tax for each period follows its own 9-month rule.
How to pay
You can pay by:
- online or telephone banking (Faster Payments, CHAPS or Bacs)
- Direct Debit, set up through your HMRC account
- debit or corporate credit card online (not personal credit cards)
- at your bank, with a payslip
You must use the 17-character payment reference for the accounting period. It starts with the company’s 10-digit UTR, so payments for different periods are allocated correctly. Allow time for the payment to clear: Faster Payments usually arrive the same or next day; Bacs takes three working days.
Interest and penalties
- Late payment interest is charged from the due date to the date of payment, at the Bank of England base rate plus 4% (since April 2025). It is deductible for Corporation Tax.
- Repayment interest is paid on overpaid tax at base rate minus 1%, with a minimum of 0.5%, and is taxable.
- There is no fixed late payment penalty for Corporation Tax for most companies, but large companies that deliberately fail to pay instalments can be penalised, and late filing brings its own penalties.
If you cannot pay on time
Contact HMRC before the deadline to ask for a Time to Pay arrangement. Interest still runs, but enforcement action is avoided while you keep to the agreement. See HMRC Time to Pay.
Frequently asked questions
When is Corporation Tax due?
9 months and 1 day after the end of the accounting period for most companies. Large companies pay in quarterly instalments.
Is the Corporation Tax payment deadline the same as the filing deadline?
No. Payment is usually due 9 months and 1 day after the period ends; the CT600 is due 12 months after.
How do I pay Corporation Tax?
Online or telephone banking, Direct Debit or corporate card, quoting the 17-character payment reference for the accounting period.
Does HMRC send a Corporation Tax bill?
No. The company calculates its own tax and must pay by the deadline without a bill.
Sources
Rates, thresholds and rules in this guide were checked against HMRC and GOV.UK guidance in October 2026. Tax rules change, so check the current position on GOV.UK or with a qualified adviser before acting. This guide is general information, not personal advice.