- Accounts to Companies House: 9 months after year-end (first accounts: 21 months from incorporation)
- CT600 and CT payment: 9 months + 1 day after year-end
- Micro-entity companies file balance sheet only publicly — P&L stays private
- Late filing penalty: £150 to £1,500 — doubles for second consecutive late filing
- Accounts must be approved by the board and signed by a director before filing
Annual accounts filing deadlines
UK private limited companies must file annual accounts with Companies House and a corporation tax return with HMRC. These are two separate filings with slightly different deadlines:
| Obligation | Deadline | Filed with |
|---|---|---|
| Annual accounts (first set) | 21 months after incorporation date | Companies House |
| Annual accounts (subsequent) | 9 months after accounting reference date | Companies House |
| CT600 return | 12 months after accounting period end | HMRC |
| Corporation tax payment | 9 months + 1 day after accounting period end | HMRC |
Example: 31 March year-end
| Obligation | Due date |
|---|---|
| Accounts to Companies House | 31 December (same year) |
| Corporation tax payment to HMRC | 1 January (following year) |
| CT600 return to HMRC | 31 March (following year) |
The Companies House accounts filing deadline and the HMRC CT payment deadline are almost identical — one day apart. In practice, most accountants prepare everything together and file both simultaneously.
What type of accounts must you file?
The level of disclosure required depends on your company's size. Most sole directors fall into the micro-entity or small company category:
| Category | Criteria (meet 2 of 3) | What must be filed publicly |
|---|---|---|
| Micro-entity | Turnover ≤ £632k, Balance sheet ≤ £316k, ≤ 10 employees | Balance sheet only — P&L is private |
| Small company | Turnover ≤ £10.2m, Balance sheet ≤ £5.1m, ≤ 50 employees | Balance sheet + notes; can omit directors' report |
| Medium company | Turnover ≤ £36m, Balance sheet ≤ £18m, ≤ 250 employees | Full statutory accounts |
| Large company | Exceeds medium thresholds | Full statutory accounts + strategic report |
Micro-entity advantage: As a micro-entity (very common for sole directors), your profit and loss account is never published on the Companies House register. The public only sees a balance sheet. This means your turnover and profitability are private — only HMRC sees the full picture via the iXBRL accounts attached to the CT600.
What the accounts must contain
Even a micro-entity balance sheet must meet Companies House requirements:
- Prepared in accordance with FRS 105 (micro-entities) or FRS 102 (small companies)
- Signed by a director (name must appear on the filed document)
- Approved by the board and dated
- Include the company name, registration number, and accounting reference date
- Comparative figures from the prior year
For HMRC (CT600), the accounts must be in iXBRL (inline XBRL) format — a structured digital format that your accountant's software or HMRC's own tools produce. This is different from the PDF filed with Companies House.
Late filing penalties
| Delay after filing deadline | Penalty (private company) | Penalty if second consecutive late filing |
|---|---|---|
| Up to 1 month late | £150 | £300 |
| 1–3 months late | £375 | £750 |
| 3–6 months late | £750 | £1,500 |
| More than 6 months late | £1,500 | £3,000 |
Penalties are imposed automatically by Companies House from the day after the deadline. There is no grace period. Penalties double if accounts are late for two consecutive years — persistent lateness can also lead to strike-off action.
Extending your accounting period
You can change your accounting reference date (year-end) by notifying Companies House via form AA01. Rules:
- You can shorten an accounting period at any time
- You can extend an accounting period only once every 5 years (without special circumstances)
- A period can be extended by up to 18 months total
- Changing year-end also changes your CT return and payment deadlines
Some directors change their year-end shortly after incorporation to align with April or March (the UK tax year), or to give more time to get their affairs in order before their first filing.
Filing accounts yourself
Directors can file accounts directly using Companies House's WebFiling service. For micro-entity accounts, this is straightforward — the online form guides you through the balance sheet fields. However, preparing the underlying accounting records, reconciling the bank account, and calculating the CT liability correctly usually requires an accountant or at minimum good accounting software.
HMRC's CT600 must be filed digitally in iXBRL format — you cannot type the return manually into HMRC's portal. Most directors use accounting software or an accountant to handle this.
Dormant companies
A dormant company (one that has had no significant accounting transactions during the period) must still:
- File dormant accounts with Companies House (simplified AA02 form)
- File a dormant CT return with HMRC (unless HMRC has confirmed no CT return is required for that period)
Filing requirements do not disappear just because a company is dormant. Missing filings for a dormant company is a common cause of Companies House strike-off action.
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Frequently asked questions
Can I file accounts myself without an accountant?
What is the accounting reference date (ARD)?
Do I need to file accounts even if the company made no money?
What is iXBRL and do I need to worry about it?
Can I reduce my accounts filing deadline by changing my year-end?
Important: This guide is for general information only and does not constitute tax or legal advice. Tax rules change — always verify current rates and thresholds with HMRC or a qualified accountant before making decisions.