How to Pay Corporation Tax: Deadlines, Methods and Penalties

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Last updated 23 October 2026. Written by the Limited Company Accountant UK team, part of Accotax. Figures are for the 2026/27 tax year; always check GOV.UK for the latest rates.

Short answer: Corporation Tax is due nine months and one day after the end of your accounting period, even though the CT600 return is not due until 12 months after. You can pay online by bank transfer, Direct Debit, debit or corporate credit card, or at your bank, and you need the 13-character payment reference from HMRC.

Key facts

Payment due	9 months and 1 day after year end
CT600 filing	12 months after year end
Large companies	Quarterly instalments if profits over £1.5 million
Late interest	Charged from the due date
Payment reference	13 characters, ending in A001 or similar

When Corporation Tax is due

The key date is the day after your accounting period ends plus nine months. For a company with a year end of 31 March 2027, the payment is due by 1 January 2028. The deadline for filing the CT600 return is twelve months after the end of the period, so 31 March 2028 for the same company.

Many directors confuse the two dates and file the return, but pay too late. HMRC charges interest from the day after the payment date, so even a short delay costs money. Put the payment date in your calendar as soon as the year end is known.

Finding your payment reference

To pay, you need your company’s 13-character payment reference, which begins with your Unique Taxpayer Reference. HMRC sends it in a letter after you register the company for Corporation Tax. It is also available through the online account. If you cannot find it, ask your accountant or contact HMRC.

Using the wrong reference is a common reason for payments not being matched, so double-check it before sending money.

Ways to pay

You can pay HMRC in several ways, and the right one depends on how quickly you need the money to arrive.

• **Online or telephone banking** using Faster Payments, which usually arrives the same day or next day.

• **CHAPS** for same-day payment, which carries a bank fee.

• **Direct Debit**, which you set up in advance and which lets HMRC collect the payment on the due date.

• **Debit or corporate credit card** online, though a fee applies for corporate credit cards.

• **At your bank or building society**, with a paying-in slip from HMRC, for some payers.

Allow for working days. If the due date falls at the weekend, the payment must reach HMRC by the last working day before it, unless you use a Faster Payment.

Quarterly instalments for large companies

Very large companies, those with profits above £1.5 million, pay Corporation Tax in quarterly instalments rather than in one go. The limit is reduced if the company has associated companies. Companies with profits above £20 million are classed as very large and pay earlier.

Most small and medium companies pay once a year, so this only matters if your profits grow. Ask your accountant to flag when you are likely to cross the threshold.

Interest and penalties on late payment

If you pay late, HMRC charges interest from the due date until the day you pay. The rate is linked to the Bank of England base rate and is reviewed regularly. There is no standard flat penalty for late payment, but if you are persistently late, HMRC may charge penalties and take enforcement action.

Late filing of the CT600 is penalised separately. The charge is £100 immediately, a further £100 after three months, and then tax-geared penalties of 10% of unpaid tax at six and twelve months. If you are late three times in a row, the flat penalty increases to £500.

What to do if you cannot pay

If you know you cannot pay on time, contact HMRC’s Business Payment Support Service before the deadline. HMRC may agree a Time to Pay arrangement that lets you pay in instalments, with interest. They are more likely to agree if you contact them early, file your return on time and propose a realistic plan.

Ignoring the problem usually makes it worse. Interest builds, enforcement starts, and a director may be personally contacted in some circumstances.

Planning your cash for the bill

The easiest way to avoid a nasty surprise is to put money aside each month. A rule of thumb is to move 20% to 25% of profit into a separate savings account as you earn it. Your accountant can give you a more accurate figure during the year, based on actual profit.

Some companies make voluntary early payments, which can earn small interest from HMRC. Whatever method you choose, make sure the money is available well before the deadline.

What happens after you pay

Once you have paid, HMRC matches the payment to your company’s Corporation Tax account using the reference. You can check the balance in your online business tax account, where payments appear within a few days. If the payment is made before you have filed the CT600, HMRC holds it as a credit until the return calculates the liability.

If you have overpaid, HMRC can repay the difference, usually into your bank account, once the return is processed. You can also ask HMRC to transfer an overpayment to another tax period if you have a future bill coming.

Common payment mistakes

The most common mistakes are using the wrong payment reference, paying the wrong amount because the figure is an estimate, forgetting that weekends and bank holidays affect the arrival date, and assuming the CT600 deadline applies to the payment too.

Another is paying the company’s Corporation Tax from a personal account without recording the payment properly. The money should be treated as a loan from you to the company, recorded in the director’s loan account, so the books stay accurate.

A simple payment calendar

A calendar makes this easier. Write down your accounting period end date. Add nine months and one day for the payment, and put a reminder two weeks earlier. Add twelve months for the CT600, with a reminder two months earlier. Then set a monthly reminder to move a share of profit into your tax savings account. If your year end is 31 March 2027, the reminders would fall around mid-December 2027 for payment, and the end of January 2028 for the return, though many companies file much earlier to settle the figure.

How your accountant helps with the payment

A good accountant does more than file the return. They calculate the liability early so you know the amount to pay, send you the exact figure and the payment reference, and remind you of the deadline. They also check that the return and payment match, because a mismatch can cause HMRC letters. If the figure turns out higher than expected, your accountant can often suggest legitimate steps before the year end, such as pension contributions or purchases, that reduce it. With fixed monthly fees, these reminders and checks are included, so the deadline does not depend on anyone’s memory.

Frequently asked questions

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