Last updated: 12 October 2026 · Written by Axel
A small limited company runs on three separate clocks, and most "Companies House deadlines" confusion comes from treating them as one. Your accounts go to Companies House 9 months after your year end. Your Corporation Tax is paid to HMRC 9 months and 1 day after the year end, and the CT600 return follows 12 months after it. Then there is the confirmation statement, which runs on a completely different date: once every 12 months, counted from when the company was set up or last confirmed. Get your year end, work out those dates once, and you will never be surprised again.
The three clocks at a glance
Two of the clocks hang off your year end (Companies House calls it the accounting reference date). The third hangs off your incorporation date. That is why they drift apart and why people miss one while hitting the others.
| What | Who it goes to | When it is due | Starts from |
|---|---|---|---|
| Annual accounts | Companies House | 9 months after year end | Year end |
| Corporation Tax payment | HMRC | 9 months and 1 day after year end | Year end |
| Company Tax Return (CT600) | HMRC | 12 months after year end | Year end |
| Confirmation statement | Companies House | Within 14 days of the end of each 12 month review period | Incorporation, or last statement date |
My honest view: the 12 month CT600 deadline is a trap. It looks generous, so people leave it, and then realise the tax was due three months earlier and the accounts a day before that. Treat the 9 month mark as your real deadline for everything except the confirmation statement.
Companies House accounts deadline
For a private company, the Companies House accounts deadline is 9 months from the accounting reference date. It is calculated to the exact day, and what counts is the date Companies House receives the accounts, not the date you sent them.
A few things worth knowing:
- Every company files accounts, including dormant ones. If yours has not traded, see what a dormant company has to file.
- You can change your year end, but only before the filing deadline for the period you want to change. Once the accounts are overdue, it is too late.
- From 1 April 2028, Companies House says accounts can only be filed using commercial software, paper filing by post ends, and abridged accounts go. Nothing to do today, but it is coming.
Corporation Tax payment deadline
This is the one people forget because there is no form attached. If your taxable profits are up to £1.5 million, you pay your Corporation Tax 9 months and 1 day after the end of your accounting period. Bigger companies pay in instalments, which is a different world and not what this guide covers.
Pay late and HMRC can charge interest. Pay early and HMRC pays you interest. You do not need to have filed your CT600 to pay, so if you know the number, pay it.
CT600 deadline
The Company Tax Return deadline is 12 months after the end of the accounting period it covers. It goes to HMRC online, separately from anything you send Companies House.
The neat way to handle it: file the CT600 at the same time as your accounts. The figures are the same, you have done the thinking once, and the 12 month deadline stops being something you need to remember. Our Corporation Tax filing deadlines page covers the edge cases.
Confirmation statement deadline
The confirmation statement is a yearly check that Companies House has the right details for your company: directors, shareholders, registered office and what the company does. It has nothing to do with your figures.
Per the confirmation statement guidance:
- You must file at least one every 12 months, even if nothing has changed.
- Your review period ends 12 months after incorporation (for your first statement) or 12 months after the confirmation statement date on your last one.
- You can file up to 14 days after the review period ends.
- It costs £50 online or £110 on paper.
- Companies House will not accept it until all directors have verified their identity, so do that well before the date rather than on it.
You can file it early, but then you pick a new confirmation statement date and the next review period starts the day after it. That is a handy way to line it up with your accounts if you like one admin day a year.
To be clear: A.X.E.L does not file confirmation statements. You file it yourself through Companies House's online service with your company authentication code. It takes a few minutes if nothing has changed.
A worked example with a 31 March year end
Take a one-director company with a 31 March 2026 year end, which last confirmed its details on 14 June 2026. Here is its calendar, in date order:
| Deadline | Date | Sent to |
|---|---|---|
| Annual accounts | 31 December 2026 | Companies House |
| Corporation Tax payment | 1 January 2027 | HMRC |
| CT600 | 31 March 2027 | HMRC |
| Confirmation statement review period ends | 14 June 2027 | Companies House |
| Last day to file the confirmation statement | 28 June 2027 | Companies House |
Check the arithmetic: 31 March plus 9 months is 31 December. One day later is 1 January. Plus 12 months is 31 March 2027. The confirmation statement is 12 months after 14 June 2026, plus 14 days.
Notice that accounts and tax land over Christmas and New Year. That is exactly when nobody wants to do paperwork, which is why a March year end company is better off filing in the summer while the year is still fresh.
The first year is different
New companies get a longer first period and a different accounts rule, and this is where the 9 month shortcut gives the wrong answer.
Your first year end is the last day of the month in which the first anniversary of incorporation falls. So the first accounts usually cover more than 12 months. For those, Companies House wants them within 21 months of incorporation, or 3 months from the year end, whichever is longer.
Example: a company incorporated on 10 June 2025 has its first year end on 30 June 2026. Its first accounts are due by 10 March 2027 (21 months from incorporation). If you just added 9 months to the year end you would get 31 March 2027, and you would be three weeks late. Check the exact date on the company's Companies House register page.
HMRC has its own wrinkle. A Corporation Tax accounting period cannot be longer than 12 months, so if your first accounts cover 13 months you file two CT600s, and each period has its own payment date. HMRC writes to you with the period dates. If the company started trading straight away, that would be 10 June 2025 to 9 June 2026, then 10 June 2026 to 30 June 2026, with tax due on 10 March 2027 and 31 March 2027. We walk through this properly on the first accounting period page.
Which misses cost you money
All four deadlines have teeth, but they bite differently:
- Late accounts: an automatic Companies House penalty starting at £150 and climbing the later you are. It is the big one for small companies.
- Late CT600: an automatic HMRC penalty starting at £200, with more added the longer it stays missing.
- Late Corporation Tax: interest on what you owe, from the day after it was due.
- Late confirmation statement: Companies House says you can be fined up to £5,000 and the company may be struck off.
For the full bands, the repeat-offender rules and how appeals work, read our guide to Companies House and HMRC late filing penalties. If you are several years behind or have had a strike-off letter, that is the point to get professional advice.
Set up reminders that actually reach you
Companies House no longer sends paper reminders by post. Its free email reminder service covers accounts and confirmation statements, and up to four people can receive them. Sign up, but do not rely on it: it says nothing about your Corporation Tax payment or CT600.
What works:
- Put all four dates in your phone calendar the day your year ends, with an alert a month before each.
- Set the accounts date as the deadline for the whole year end job, CT600 and tax payment included.
- Keep the company authentication code and your Government Gateway login somewhere you can find them, so deadline week is not spent on password resets.
Quick answers
Frequently Asked Questions
01When are company accounts due at Companies House?
For a private company, 9 months after the accounting reference date (your year end). First accounts covering more than 12 months are due 21 months after incorporation, or 3 months after the year end if that is later.
02Is the CT600 deadline the same as the Corporation Tax payment deadline?
No. The CT600 is due 12 months after the end of the accounting period, but the tax itself is due 9 months and 1 day after it for most small companies. The money comes first.
03When is my confirmation statement due?
Within 14 days of the end of your review period, which ends 12 months after incorporation or after your last confirmation statement date. It has nothing to do with your year end.
04Does a company with no profit still have to file?
Yes. Accounts and the confirmation statement are due whether or not the company made money, and the Companies House penalty depends only on lateness. Dormant companies have lighter accounts but still file.
05Can I file my accounts and CT600 at the same time?
Yes, and it is the sensible way to do it. Filing both by the 9 month accounts deadline means the CT600 is early rather than nearly late.
File the year end clocks together
If your company is a simple micro-entity, you can handle the two year end clocks yourself. A.X.E.L Filing prepares your micro-entity accounts and CT600 and files them to Companies House and HMRC with your own Government Gateway login: £49 for both, no subscription. File them together, pay the tax, and the only date left in your diary is the confirmation statement.
A.X.E.L Filing
Accounts and CT600, filed in one sitting.
Prepare your micro-entity accounts and Corporation Tax return together, then file them to Companies House and HMRC yourself. No accountant fees, no subscription.
£20 for a dormant company
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