Corporation tax is due nine months and one day after the end of the accounting period for companies with taxable profits of up to £1.5 million, per gov.uk, and by instalments during the period for companies above that. The return is due later, twelve months after the period end, so the payment comes before the return, which is the order that catches first-year directors. This page sets out the deadline, what instalments and payments on account mean for a larger company, whether HMRC will take a smaller company's tax in stages, how to find the reference number a payment needs, and what the activation code is for. It is written for the director paying the bill themselves rather than through an accountant, and the free UK corporation tax calculator on this site works the amount.
Nine months and one day, for almost every small company
For taxable profits up to £1.5 million the deadline is nine months and one day after the end of the accounting period, per gov.uk: a 31 March year end pays by 1 January. The accounting period is usually the company's financial year, but a new company often has two periods in its first year because the period cannot exceed twelve months, and each has its own payment date. HMRC charges interest on late payment, at 7.75 percent from 9 January 2026, and pays interest on early payment, at 2.75 percent from the same date, per gov.uk's interest rates.
Quarterly corporation tax payments and payments on account
Companies with taxable profits over £1.5 million pay by instalments, per gov.uk, and above £20 million on an accelerated schedule; the limits are divided by the number of associated companies, so a group of four is in instalments at £375,000 each. The instalments are estimates paid during the period, in effect corporation tax payments on account, trued up when the return is filed. A small company does not make payments on account for corporation tax at all, which is a point of confusion with self assessment, where the director's own tax is paid that way.
Can you pay corporation tax in installments if the company is small
Not as of right. Below the instalment limits the whole amount is due on the one date, and a company that cannot pay should contact HMRC before the deadline about a Time to Pay arrangement, which spreads the debt with interest running. It is an agreement, not an entitlement, and a company that simply pays late without one is charged interest and, for repeated failure, can face penalties. The pattern to avoid is the accountant's bill and the tax bill landing in the same month with nothing set aside; the calculator's figure, read at the year end, is nine months' notice of the amount.
The reference number and the activation code
Every payment needs the 17-character corporation tax payment reference number for the accounting period it belongs to, which is on the notice to deliver a return, on HMRC's reminders and in the company's HMRC online account, per gov.uk; the last digits change with the period, so last year's reference sends this year's money to the wrong period. The corporation tax activation code is the code HMRC posts to the registered office after the company enrols for corporation tax online, and it has to be entered within its expiry to activate the service. Neither is the company's UTR, though the reference starts with it.
Questions people ask about when is corporation tax due
What if my company has no tax to pay?
There is nothing to pay by the payment date, but the return is still due twelve months after the period end if HMRC has sent a notice to deliver one, and a nil return filed late still attracts the £200 penalty.
How do I pay?
By Faster Payments, CHAPS, online banking or debit card for same or next day, or by Bacs and Direct Debit with three to five working days, per gov.uk. Corporation tax cannot be paid by post. Allow the clearing time before the deadline, not after it.
Where does the activation code come from?
HMRC posts it to the registered office once the company has enrolled for the online service. It expires, and a company that misses it requests a new one through the online account; nothing on this site or anywhere else can generate it.