How to pay corporation tax
Corporation tax is due 9 months and 1 day after the end of the accounting period — three months before the CT600 return itself. You pay HMRC directly by bank transfer, direct debit or card, quoting the 17-character reference for that specific accounting period. Interest runs automatically from the day after the deadline.
The deadline that surprises directors is not the return — it is the payment, which falls three months earlier. Everything else about paying is straightforward once that is in the diary.
Work out the date
Take your accounting period end and add nine months and one day. A 31 March year end means 1 January; a 31 December year end means 1 October. That is the date the money must reach HMRC — not the date you send it.
Then note the return date separately: 12 months after the end of the accounting period. Two dates, three months apart, in that order. Directors who diary only the later one are the reason interest exists.
Work out the amount
This is the part that makes the deadline awkward: you have to know the figure before the return is due. Taxable profit is not the profit in your accounts — entertaining is added back, depreciation comes out, capital allowances go in. The corporation tax calculator gives an order of magnitude from a profit figure, including marginal relief.
In practice the sensible rhythm is to prepare the accounts shortly after the year end rather than shortly before the filing deadline. It costs nothing extra and turns the payment date from a guess into a known number.
How to pay
- Faster Payments, CHAPS or Bacs from the business account — same or next day for Faster Payments, three working days for Bacs.
- Direct debit — the first one takes about five working days to set up, so it is not a same-week option.
- Debit or corporate credit card online.
- At your bank with a paying-in slip, if you still have one.
Weekends and bank holidays count against you: if the deadline falls on one, the money needs to arrive before it.
The reference is not what people expect
Corporation tax is paid against a 17-character reference specific to one accounting period, not against a permanent company number. Use last year's and the payment is applied to last year — producing a demand for the tax you just paid and an unexpected refund of the tax you paid before. Untangling it takes weeks.
Not sure what you owe, or when?
Send us your year end date and last year's accounts. We will tell you both dates, the figure, and what could still legitimately reduce it — before the deadline rather than after.
Ask on WhatsAppOr send an email
Free assessment first. If there is work to do, you get a fixed quote in writing before anything starts.
If you cannot pay
Say so early. HMRC agrees instalment arrangements routinely, and one agreed before the deadline is a normal administrative act; the same request after enforcement has started is a negotiation from a worse position. Interest still runs, but the escalation stops.
What does not work is filing nothing and hoping. HMRC estimates the bill itself after six months, and its estimate is not designed to flatter you.
Questions people ask
When exactly is corporation tax due?
9 months and 1 day after the end of the accounting period. For a year ending 31 March, that is 1 January. The return is not due until 12 months after the end of the accounting period — so the money leaves three months before the paperwork does.
How do I know what to pay if the return is not done?
You compute it, or we do. The payment deadline does not wait for the return to be filed, so the practical approach is to prepare the accounts early enough to know the figure — which is the main reason we ask clients for their records well before the year is out of time.
What is the 17-character reference?
A payslip reference unique to one accounting period — not a permanent number for the company. Reuse last year's and the payment lands against the wrong period, which produces a demand for tax you have already paid and a refund you did not ask for.
What if I pay late?
Interest runs from the day after the due date. It is charged automatically and there is no reasonable-excuse defence against interest — it is compensation for late money, not a penalty. Late filing of the return is penalised separately.
Can I pay in instalments?
Very large companies are required to, on a quarterly cycle. For everyone else instalments mean a Time to Pay arrangement with HMRC, agreed in advance. Arranging one before the deadline is a different conversation from explaining a missed payment afterwards.
What if the company made a loss?
Then there is no corporation tax to pay — but you still have to file the return saying so, and you should still tell HMRC there is nothing due. Losses can often be carried back against a previous profitable year or forward against future profits, which is worth getting right rather than leaving on the table.
Figures are for the tax year shown and change every April. They are general information, not advice — we check the current position for your circumstances before anything is filed.
Reviewed 19 October 2026.
Part of our work on company and director tax — if you want someone to take it off your hands, start with our how to pay yourself from a limited company page.