Corporation tax payment and deadlines

The two corporation tax dates, and why they differ #

Every other tax you will meet asks you to file first and pay afterwards. Self Assessment does it, VAT does it, PAYE does it. Corporation Tax reverses the order, and it is not an accident: HMRC wants the money before it wants the paperwork.

• Pay 9 months and 1 day after the end of the accounting period.
• File the CT600 12 months after the end of the accounting period.

The practical consequence is that you have to know your corporation tax amount, accurately enough to pay it, three months before you are required to declare it. Companies that leave their accounts until the filing deadline discover the payment deadline went past a quarter of a year earlier, and interest has been running ever since.

Note also that these are HMRC deadlines. Companies House has its own, separate deadline for the annual accounts, normally nine months after the year end for a private company. Three different dates hang off one year end, and they are not interchangeable.

There is a fourth, unrelated to any of them: the confirmation statement to Companies House, due once a year on the anniversary of incorporation or of the last one filed. A confirmation statement for Companies House is not a tax return and confirms only that the company's registered details are correct. Missing it does not attract a tax penalty but it can eventually lead to the company being struck off.

The words get used interchangeably when they should not be. The corporation tax due date is when the money must be with HMRC: nine months and one day after the period end. The corporation tax submission deadline is when the return must be filed: twelve months after it. If someone tells you the deadline is twelve months, they are talking about the return, and the money was due three months before that.

When your corporation tax payment is due #

Take the last day of your accounting period, add nine months, then add one day. The one day matters and it is not decoration: it is what turns a month-end into the first of the following month. These are the corporation tax dates for the most common year ends.

Watch the month-end cases. A period ending 31 May is due on 1 March, not 3 March. Nine months from 31 May lands in February, which has no 31st, so the date clamps back to the end of February and the extra day takes it to 1 March. Several online calculators get this wrong by letting the overflow run forward.

The corporation tax calculator works out both dates from your year end alongside the tax itself.

How to pay corporation tax #

There is no single corporation tax online payment button that suits everyone, because the methods clear at different speeds and the deadline is the day the money reaches HMRC, not the day you send it. If the deadline is a weekend or bank holiday, the money has to be there the working day before.

You cannot pay Corporation Tax by personal credit card, and you cannot pay at the Post Office. If you are setting up a Direct Debit for the first time, start five working days out, because a new mandate does not clear as quickly as one already in place.

Corporation tax payment details and bank details #

You do not need corporation tax HMRC bank details at all if you pay from inside your HMRC online account, because the corporation tax payment details are filled in for you and the reference is attached automatically. That is the route least likely to go wrong.

If you are paying from your own banking app instead, take the account number, sort code and account name from GOV.UK on the day rather than from an old email or a saved payee. HMRC uses different accounts for different taxes, and the details do change occasionally.

The corporation tax reference number for the payment is the 17-character one described below, not the company UTR. That distinction is the single most common reason a correctly sized payment ends up in the wrong place.

Your payment reference is not your UTR #

The corporation tax UTR, the Unique Taxpayer Reference, identifies the company. HMRC posts it to the registered office shortly after incorporation and it stays the same for as long as the company exists. You need it to sign in, to authorise an accountant, and to file.

The 17-character payment reference identifies one accounting period. It is on the notice to deliver your return, on HMRC's reminders, and in your online account. Reuse last year's and the money lands against last year, your current bill stays unpaid, and interest keeps running while a payment of exactly the right amount sits in the wrong place. Check it every year rather than saving it in your banking payees and forgetting.

Your corporation tax online account #

The corporation tax account is part of HMRC's Business Tax Account. It is where you find the payment reference, see what HMRC thinks you owe, check whether a payment has been allocated, and file the return for a straightforward company.

Getting in needs the Government Gateway user ID and password for the company, not your personal one, plus the company UTR. If nobody at the company has ever signed in, that enrolment is a job with a postal activation code in the middle of it. Start it well before a deadline rather than on the day.

Making Tax Digital for limited companies #

Making Tax Digital for limited companies already applies to VAT: a VAT registered company must keep digital records and file through compatible software. That has been compulsory for some years and is not optional.

For Corporation Tax it has not arrived. Making Tax Digital for Corporation Tax has been discussed and repeatedly deferred, and no start date currently applies to company profits. A company filing a CT600 today files it annually as it always has.

So MTD is a VAT obligation now and a Corporation Tax possibility later. Anything telling you that Corporation Tax has moved to quarterly reporting is describing a proposal rather than the current position.

Filing the corporation tax return #

The corporation tax return is form CT600, and the corporation tax submission is not one document but three filed together: the CT600 itself, the statutory accounts, and the tax computations that bridge the accounting profit to the taxable profit. All three must be filed online, and the accounts and computations have to be in iXBRL, a tagged format.

HMRC's own free filing service covers unrepresented companies with straightforward affairs. Companies outside that, including most with associated companies, property income or any complexity, need commercial software or an accountant. That requirement, rather than the tax itself, is why a lot of small companies end up paying for corporation tax services at all.

File even when there is nothing to pay. If HMRC has issued a notice to deliver a return, a return is due. A loss, a dormant trading year or a company that never got going does not excuse it, and the penalties below apply to a nil return exactly as they do to a profitable one.

Corporation tax interest rates, and what paying late costs #

There is no fixed penalty for paying Corporation Tax late. There is interest, and it runs from the day after the due date until the day the money arrives. That is the first thing to understand here: there are no corporation tax late payment penalties as such, unlike VAT and Self Assessment, where paying late attracts a percentage charge on top.

The corporation tax interest rates are not fixed percentages. They track the Bank of England base rate, so they move whenever it does, and they are deliberately asymmetric.

That margin rose from 2.5 points on 6 April 2025, so anything quoting base rate plus 2.5% is describing the old regime. The gap between the two rows is the point: paying late is charged at a commercial rate, paying early earns almost nothing, and neither is a sensible way to manage cash.

Corporation tax interest is deductible for a trading company, which softens it a little, but not nearly enough to make late payment a sensible way to fund the business. Interest is not a penalty and is not appealable: it is simply the price of holding money that was due.

Penalties if you file late #

The return is where the penalties live. These are charged whether or not any tax is owed.

At six months HMRC stops waiting and issues a determination: its own estimate of the tax, which becomes legally due. You cannot appeal a determination. The only way out is to file the actual return, which replaces it. That is why a very late return is worth filing even when the deadline is long gone.

Corporation tax late filing penalties are the ones with fixed amounts. The asymmetry with interest is deliberate and worth using: if you cannot pay, filing on time still avoids these penalties entirely and leaves only interest running on the unpaid tax.

Quarterly instalments for larger companies #

Above a certain size the single payment date disappears and corporation tax instalments take over. A company is large if profits exceed £1,500,000.00, and very large above £20,000,000.00.

• Large: four instalments, in months 7, 10, 13 and 16 of the accounting period.
• Very large: four instalments, in months 3, 6, 9 and 12.

For a large company with a 12 month period, two of the four fall before the period has ended. You are paying tax on profits you have not finished earning, based on a forecast, and getting the forecast wrong carries interest either way.

Two things soften the edge. A company is not treated as large if its Corporation Tax bill is £10,000.00 or less. And a company crossing the threshold for the first time gets a year of grace, unless profits exceed £10,000,000.00.

The threshold is shared, exactly as the rate limits are. Divide £1,500,000.00 by the number of associated companies plus one. A group of four companies is into instalments at £375,000 of profit each.

These instalments are what corporation tax payments on account means for a company. If a loss later reduces the liability, instalments already paid for that period can be reclaimed.

Contacting HMRC about Corporation Tax #

Searches for a corporation tax phone number, a corporation tax telephone number or a corporation tax HMRC contact route all want the same thing, and the honest answer is to take it from GOV.UK rather than from a third party. HMRC publishes its own contact numbers and opening hours, they change, and numbers republished elsewhere go stale or, worse, belong to paid call-forwarding services.

Before ringing, most of it can be done in the Business Tax Account: checking what HMRC thinks you owe, finding the corporation tax number HMRC holds for you, seeing whether a payment has been allocated, and filing a straightforward return. Corporation tax sign in is through the Government Gateway credentials for the company rather than your personal ones.

If nobody has ever signed in for the company, enrolment involves a corporation tax activation code sent by post, which has a limited life and has to be used before it expires. That is a job to start weeks before a deadline, not on the day.

Corporation tax payment plan options #

If the bill cannot be paid in full, a corporation tax payment plan is a Time to Pay arrangement with HMRC. Corporation tax time to pay spreads the debt, usually over a few months, and it is agreed far more readily when you ask before the due date than after a debt has been chased.

Contact HMRC before the deadline, not after. Interest still runs for the whole period. What an arrangement buys is the absence of enforcement, not free credit.

File the return on time regardless. Filing and paying are separate obligations with separate consequences, and there is no reason to collect filing penalties on top of a payment problem you have already declared.

Common questions #

When is corporation tax due?

Corporation Tax is due 9 months and 1 day after the end of your accounting period. A company with a 31 March year end must pay by 1 January. This is the payment deadline, not the filing deadline, which comes three months later.

What is the deadline for the corporation tax return?

The Company Tax Return, form CT600, is due 12 months after the end of your accounting period. A 31 March year end means the return is due by the following 31 March, three months after the tax itself had to be paid.

How do I pay corporation tax online?

Sign in to your HMRC online account and pay by approving a payment through your bank, by Faster Payments, by CHAPS, or by debit card. Those reach HMRC the same or next day. Bacs and an existing Direct Debit take three working days, and a new Direct Debit takes five.

Is the corporation tax payment reference the same as my UTR?

No. Your UTR is 10 digits and stays the same for the life of the company. The Corporation Tax payment reference is 17 characters and is different for every accounting period. Paying with the wrong one is the most common reason a payment is not matched to the right year.

What happens if I pay corporation tax late?

HMRC charges late payment interest from the day after the due date until you pay, currently 7.75%. There is no separate late payment penalty for Corporation Tax, but filing the return late carries penalties of its own.

Do I still have to file if the company made no profit?

Yes. If HMRC has sent a notice to deliver a Company Tax Return you must file one, even if there is no tax to pay. A loss-making or dormant-in-practice company that ignores the notice still collects the late filing penalties.

When do quarterly instalments start?

When profits exceed £1.5 million, divided by the number of associated companies plus one. A company crossing that line for the first time gets a year of grace unless profits exceed £10 million. Very large companies, above £20 million, pay earlier still.