SimpleReturns

What is box 475 on the CT600? (the tax you owe)

Reviewed by Lee Jones, Founder · Updated 16 July 2026
The short answer

Box 475 is the Corporation Tax your company owes for the year, after any reliefs have been taken off. HMRC calls it your "Net Corporation Tax liability". For most small companies it is the actual bill, due 9 months and 1 day after your accounting period ends. That is earlier than the deadline for sending the return itself, which catches a lot of people out.

Official source. This guide is a plain-English summary of official GOV.UK guidance, not advice. The authoritative source is The Company Tax Return guide on gov.uk. Always rely on that over our summary.

What goes in it?

Box 475 is a simple subtraction: the tax worked out in box 440, minus any special reliefs totalled in box 470. Box 440 is your company's Corporation Tax chargeable, the tax worked out on your profit at the right rate, after any marginal relief discount has come off. Box 470 collects rarer reliefs, such as tax already paid abroad on the same money, and for most small UK companies it is zero.

Say your company made a taxable profit of £40,000. That is under £50,000, so it is all taxed at 19%, giving £7,600 in box 440. With nothing in box 470, box 475 is £7,600. That is the tax your company owes.

A few extra charges can be added further down the form, such as tax on money the company lent to its directors or shareholders. If none apply, and for most small companies none do, box 475 carries straight through to the final "tax payable" figure at the bottom of the calculation. Box 475 is the number that matters.

When do I have to pay it, and how?

Your Corporation Tax is due 9 months and 1 day after the end of your accounting period. So if your company's year ended on 14 June 2026, the tax is due by 15 March 2027.

You cannot pay by post. Pay by bank transfer, debit card, or Direct Debit. A Faster Payment usually reaches HMRC the same day or the next day, a Bacs payment takes about 3 working days, and a new Direct Debit takes about 5 working days to set up, so do not leave that one to the last minute.

One detail really matters: the reference. HMRC gives your company a 17-character Corporation Tax payment reference, different for every accounting period. It is on the "notice to deliver your tax return" letter, on HMRC payment reminders, or in your company's HMRC online account. Use the wrong one, for example last year's, and your payment can be delayed.

Pay late and HMRC may charge you interest. Pay early and HMRC pays you a little interest, a rare treat from the tax office.

What usually goes wrong?

The classic trap is mixing up the two deadlines. Your Company Tax Return does not have to be filed until 12 months after your accounting period ends, but the money is due at 9 months and 1 day. The payment deadline lands just under three months before the filing deadline.

Plenty of directors relax because "the return isn't due for ages" and then discover the bill was due months earlier, with interest building up. The safe habit is to treat 9 months and 1 day as the real deadline and file the return around the same time, since you cannot know the exact bill until the return's calculation is done anyway. Filing late has its own sting on top: a £200 penalty from the very first day.

Do I have to work this out myself?

No. Your filing software works box 475 out from the earlier boxes; nobody does this subtraction by hand. SimpleReturns goes further back: it builds the whole calculation from your business bank statement and a few plain-English questions, fills box 475 and every box before it, and shows you the figure and the payment deadline before anything is sent. You check it, we file it, £99 flat for both filings, the tax return to HMRC and the accounts to Companies House.

If your company is part of a group, or its profits are over £1.5 million, the payment rules work differently and an accountant is honestly the right choice.

Common questions

Is box 475 the amount I actually transfer to HMRC?

For most small companies, yes. A few extra charges can be added after it, such as tax on money the company lent to a director. If none apply, the final figure at the bottom of the form is the same as box 475.

What if my company made a loss and box 475 is £0?

Then there is nothing to pay, but you still have to file the return by the deadline. The £200 late filing penalty applies even when no tax is due.

Where do I find the payment reference?

In your company's HMRC online account, on the "notice to deliver your tax return" letter, or on any HMRC payment reminder. It changes every accounting period, so grab the one for the year you are paying.

Want box 475 filled in for you?

SimpleReturns works out the tax from your bank statement and a few plain-English questions, and fills box 475 for you. You review every figure before anything is sent. Free to start, no card needed, £99 flat when you file.

Start your return

And if your company is in a group or over the £1.5 million profit mark, we will say plainly that an accountant is the better route.

General guidance, not advice. This guide explains how the rules generally work for small UK limited companies. It isn't tax advice for your specific situation, if you're unsure, check with us or an accountant.