Your first accounts are not due when you think
Every year after your first, your accounts are due nine months after your financial year ends. That rule is simple and everybody learns it, but it is the wrong rule for your first set.
First accounts are due 21 months after the date you registered, or three months after your accounting reference date, whichever is longer. It is a completely different calculation off a completely different starting point.
The reason to take this seriously is what happens when you get it wrong. Companies House's own guidance on appealing a penalty lists "these were your first accounts" as a reason an appeal will fail. It is on the list because people try it, and they try it because the nine month rule is the only one they had ever been told.
The two tax returns nobody budgets for
This one costs money twice and surprises almost every new director.
Companies House sets your accounting reference date to the last day of the month your first anniversary falls in. Incorporate on 11 May 2024 and your first accounts run to 31 May 2025. In gov.uk's own words that is "12 months and 3 weeks".
HMRC will not accept a period that long. Its rule is absolute: the period covered by your tax return cannot be longer than 12 months. So your first accounts get split into two accounting periods, and you file two Company Tax Returns with two payment deadlines. For that 11 May incorporation, gov.uk's own example puts them at 11 February 2026 and 1 March 2026.
And it is not bad luck, it is arithmetic
It is worth being precise about this, because "it usually happens" and "it always happens" lead to different behaviour.
The default reference date is the last day of the anniversary month. The twelve month point is the day before the anniversary. The last day of a month is never earlier than a date inside that month, so the reference date is always later than the twelve month point, so the first period always runs over. Incorporate on the 31st and the second period is a single day long, and you still file a full return for it.
So this is not something that catches unlucky companies. With a default reference date it catches every single one.
The fix is free and takes five minutes
Shorten your accounting reference date to the day before your first anniversary.Your first accounts then cover exactly twelve months, there is one Corporation Tax accounting period, one return and one payment date.
Companies House lets you change your accounting reference date, shortening is unrestricted, and it costs nothing. This page gives you the exact date to shorten it to. It is one of the more useful pieces of admin a brand new company can handle early, and it is almost never mentioned, because the people who would tell you are the people you have hired to file two returns.
The penalty, and the bit where it doubles
For a private company or an LLP, measured from the deadline:
- Up to 1 month late: £150
- 1 to 3 months: £375
- 3 to 6 months: £750
- More than 6 months: £1,500
A public company pays £750, £1,500, £3,000 and £7,500 on the same bands. The penalty is automatic: it is issued because the accounts were late, not because anybody weighed it up.
Companies House puts it plainly: the late filing penalty will be doubled if accounts are filed late in two successive financial years. A second slip is not another £150, it is £300. Drift past six months twice and it is £3,000. One on-time year in between resets it.
The confirmation statement, which is not accounts
Separate filing, separate deadline, and the one most likely to be forgotten because there is usually nothing to report. It is a confirmation, not a change notification: you file it to say the record is still right, and "nothing has changed" is a complete answer that still has to be given.
Your review period ends twelve months after incorporation, or twelve months after your last statement, and you have fourteen days after that to file. £50 online, £110 on paper, which is an expensive stamp. Not filing one can mean a fine of up to £5,000 and the company being struck off the register.
Why the tax is due before the return
Corporation Tax is payable nine months and one day after your accounting period ends. The Company Tax Return that calculates it is not due until twelve months after it ends.
So you pay first and file up to three months later, which looks like an error and is not. In practice you work the figure out in time to pay it, and the return is a formality you complete whenever it suits after that.
Common questions
When are my first accounts due?
Twenty-one months after the date you registered with Companies House, or three months after your accounting reference date, whichever is longer. Not nine months after your year end. That nine month rule is real, but it starts with your second set of accounts, and confusing the two is common enough that gov.uk's own appeal guidance lists "these were your first accounts" as a reason an appeal will fail. A public company gets eighteen months instead of twenty-one, and six months instead of nine.
Why do I have two Corporation Tax returns?
Because Companies House and HMRC measure the year differently and neither will bend. Companies House sets your accounting reference date to the last day of the month your first anniversary falls in, so your first accounts run slightly over twelve months. HMRC will not accept that: in its own words, the period covered by your tax return cannot be longer than 12 months. So the period splits into a full twelve months and a short remainder, and each one needs its own Company Tax Return and its own payment date.
Can I avoid the two tax returns?
Yes, and it costs nothing. Shorten your accounting reference date to the day before your first anniversary, so your first accounts run exactly twelve months, and there is one accounting period, one return and one payment date. Companies House lets you make that change, and almost nobody is told they can. This page gives you the exact date to shorten it to.
How much is the late filing penalty?
For a private company or LLP: £150 if you are up to a month late, £375 for one to three months, £750 for three to six months, and £1,500 beyond six months. Public companies pay £750, £1,500, £3,000 and £7,500 on the same bands. The penalty is automatic. It is issued because the accounts were late, not because anybody decided you deserved it.
Does the penalty really double?
Yes, and it turns a nuisance into a real problem. Companies House puts it plainly: the late filing penalty will be doubled if accounts are filed late in two successive financial years. So a second slip is not another £150, it is £300, and if you drift past six months twice it is £3,000 rather than £1,500. The doubling looks at consecutive financial years, so one good year in between resets it.
Do I still file a confirmation statement if nothing has changed?
Yes. It is a confirmation rather than a change notification, and that is why it gets forgotten: there is nothing to report, so it does not feel like there is anything to do. Your review period ends twelve months after incorporation, or twelve months after your last statement, and you have fourteen days after that to file. It costs £50 online and £110 for the paper form. You can be fined up to £5,000 and the company can be struck off for not filing one.
Why is my Corporation Tax due before my tax return?
It genuinely is, and it reads like a mistake the first time you see it. Payment is due nine months and one day after your accounting period ends. The return that works out how much you owe is not due until twelve months after it ends. So you are expected to calculate and pay, then formally tell HMRC the figure up to three months later. In practice you do the sums in time to pay, and file the return whenever it suits after that.