Your UK company files annual accounts with Companies House once a year. For a private limited company the deadline is 9 months after your accounting reference date — except your very first set, which is due 21 months after incorporation. Miss it and the penalties start at £150 and climb to £1,500, automatically.
The part that trips founders up isn’t the maths. It’s that Companies House accounts are one of three separate UK filings, and people assume doing one covers the others. It doesn’t. Here’s how accounts work, what you can file as a small company, and where the Corporation Tax return fits in.
Accounts are not your confirmation statement, and not your tax return
Three obligations, three recipients, three deadlines. Confuse them and you’ll think you’re compliant when you’ve done a third of the job.
| Annual accounts | Confirmation statement | Corporation Tax (CT600) | |
|---|---|---|---|
| Filed with | Companies House | Companies House | HMRC |
| Reports the company's finances | |||
| Confirms who runs the company | |||
| Required even if dormant | |||
| Deadline | 9 months after year end | Yearly review period | 12 months after year end |
Annual accounts are about money, filed to Companies House. The confirmation statement is about identity, also filed to Companies House. The CT600 is about tax, filed to HMRC. We’ll come back to the CT600 at the end, because conflating it with your accounts is the single most common UK filing mistake.
When your accounts are due
The deadlines hang off your accounting reference date (ARD) — by default, the anniversary of the last day of the month you incorporated. Incorporate on 14 March 2026 and your first ARD is 31 March 2027.
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Your first accounts — 21 months after incorporation
The first accounting period runs from incorporation to your first ARD, so it’s usually longer than 12 months. To allow for that, your first accounts get an extended deadline: 21 months from the date you incorporated.
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Every set after that — 9 months after the ARD
Once the company is established, a private limited company files its accounts within 9 months of the end of each accounting period. A 31 March year end means a 31 December filing deadline.
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Shorten or extend the period if you need to
You can change your ARD to move the deadline, within limits — you can shorten a period as often as you like, but extend it only once every five years. Plan this before the deadline, not after.
It’s not the date you posted them or hit submit. If your accounts are rejected and you have to resubmit after the deadline, you’re late. Build in a buffer — especially for a first filing, where there’s a real chance of a kicked-back submission.
What you can file as a small or micro company
Most non-resident founders run small companies, and the rules let small companies file less. You qualify for a size bracket by meeting at least two of three thresholds for turnover, balance-sheet total, and employees. The smaller the company, the simpler the accounts.
Historically small companies could file very stripped-back accounts. Under the Economic Crime and Corporate Transparency Act, Companies House is moving small and micro companies towards filing a profit and loss account, narrowing the options that let companies show almost nothing on the public register. Expect to disclose more than you used to, even as a micro-entity.
Filing is going software-only
How you file is changing too. Companies House is phasing out web and paper filing for accounts and moving to software-only filing under ECCTA. The free WebFiling service and posted paper accounts are being retired; accounts will need to be submitted through commercial software that’s compatible with Companies House (and, ideally, files to HMRC at the same time).
For a non-resident founder this is mostly good news — software filing is faster, gets validated before submission, and reduces rejections. But it does mean the “fill in a form on GOV.UK” route you may have read about is going away. You’ll either use accounting software that supports it or have an agent file for you.
Late filing penalties
These are automatic, escalating, and charged by Companies House regardless of why you were late. For a private company:
| How late | Private company penalty |
|---|---|
| Up to 1 month | £150 |
| 1 to 3 months | £375 |
| 3 to 6 months | £750 |
| More than 6 months | £1,500 |
File late two years in a row and the penalty for the second year is doubled — so a more-than-six-months delay becomes £3,000. Companies House rarely waives these; “I forgot” and “I live abroad” are not accepted excuses. Persistent failure can also lead to the company being struck off and directors facing enforcement.
The penalties for accounts are separate from anything HMRC charges for a late tax return. You can be late with both and collect two sets of penalties from two different bodies.
The CT600 is a different filing entirely
Here’s the one to burn into memory. Your Corporation Tax return — the CT600 — goes to HMRC, not Companies House. It reports your taxable profit and works out the tax due. It’s due 12 months after the end of your accounting period, and confusingly the tax itself is payable earlier — normally 9 months and one day after the period ends.
In practice good software files the accounts to Companies House and the CT600 plus computations to HMRC from one process, which is why software-only filing and the CT600 are converging. But they remain two filings, to two organisations, with two deadlines and two penalty regimes. Treat them as one and you’ll miss one of them.
We file both for cross-border founders — the Companies House accounts and the HMRC Corporation Tax return — from one set of figures, on time, so you don’t collect penalties from two directions.
File your UK accounts on time
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