The first time you file company accounts feels like a test you didn’t study for. The forms ask questions you’ve never thought about, the deadlines are oddly long but easy to forget, and the penalties for missing them rise faster than your bank balance. The reality: for most small companies, accounts are simpler than you think. This guide walks through what you actually need to file, when, and how to do it without an accountant if your company is straightforward.
What “company accounts” actually means
“Company accounts” is shorthand for two related but separate things. The first is the statutory accounts you file at Companies House, which become a public record. The second is the Company Tax Return (the CT600) you file with HMRC, with a full set of accounts and a Corporation Tax computation attached. The CT600 stays private. Both filings come from the same underlying numbers, but they’re distinct submissions with distinct deadlines and distinct audiences.
Most small companies file abridged or filleted accounts at Companies House – a slimmed-down version that omits the profit and loss account and the director’s report from the public register. HMRC, meanwhile, receives the full version. That asymmetry is deliberate: the public record exists for transparency about who owns and runs the company, while the tax authority sees the financial detail it needs to assess Corporation Tax.
Deadlines you must hit
Three dates matter for a typical small Ltd. Your first set of accounts is due 21 months after the date of incorporation, which gives you a long runway because the first accounting period can stretch up to 18 months. Subsequent accounts are due 9 months after the end of each accounting period, the so-called accounting reference date (ARD). Corporation Tax itself must be paid 9 months and 1 day after the end of the period; the CT600 is technically due 12 months after the period end, but in practice everyone files at the payment date because you can’t calculate the tax to pay without doing the return.
A practical wrinkle: your accounting reference date doesn’t have to line up with the tax year. Companies House defaults the first ARD to the end of the month a year after the month of incorporation. You can change it later (form AA01) if you want a tidier year-end, but rule the change in early – not at the next deadline.
Are you a micro-entity, small or medium-sized company?
Companies House classifies companies by size, and the size sets the reporting bar. The thresholds were uplifted in April 2025 to reflect inflation. To qualify as a micro-entity you must meet at least two of three tests: turnover not over £1m, balance-sheet total not over £500,000, and an average of 10 or fewer employees. To qualify as small, the equivalent thresholds are £15m turnover, £7.5m balance sheet, and 50 employees. Above small you’re medium or large, with progressively more reporting and audit obligations.
Most one-or-two-person Ltds qualify as micro-entities and can file under the FRS 105 standard, which keeps the accounts short. The size category is decided by the accounting period – if you’ve grown over the thresholds, the next period drops you up a tier even if last year was below.
What goes into a small or micro-entity set of accounts
A micro-entity set of accounts contains a statutory-format balance sheet, a small number of explanatory notes, and (if you don’t fillet) a condensed profit and loss account. A small company set adds a director’s report and more detailed notes, but is still significantly lighter than a medium or large company’s accounts. Everything is FRS 105 (micro) or FRS 102 Section 1A (small) – British accounting standards designed for the size.
The version you file at Companies House can be filleted: the P&L and the director’s report removed before the filing, leaving only the balance sheet and minimal notes on the public record. Most small Ltds fillet, because the public version of the P&L gives competitors more than they need. HMRC always sees the full version.
Filing options at Companies House
There are four routes. WebFiling is Companies House’s own free online service – good if you only need to file at Companies House, but it doesn’t talk to HMRC. Software filingis what most accountants use; it talks to both HMRC and Companies House. Joint filing via HMRC is the route most small directors should take: one submission, both filings, free. Paper filingis still possible but slow, error-prone, and Companies House are incrementally retiring it.
Step-by-step: filing through HMRC’s joint service
For a straightforward small or micro-entity company, the joint filing service is the cleanest route. Allow 60-90 minutes the first time; subsequent years are quicker once you know the system.
- Sign in to HMRC. Use your Government Gateway ID for the company. If you haven’t already enrolled for Corporation Tax online, you’ll need to do that first; allow a few days for HMRC to post you the activation code.
- Open the “File a Company Tax Return” service. Choose the accounting period you’re filing for.
- Complete the CT600. Most lines auto-populate from the accounts you upload. Confirm the trade description, turnover, profit, and any reliefs you’re claiming.
- Attach the statutory accounts. Upload or build them in the format your size requires (micro-entity, abridged, or full).
- Choose joint filing. Tick the box to file the same accounts at Companies House at the same time. This avoids a separate Companies House submission.
- Submit the Corporation Tax computation. Add the computation showing how taxable profit is derived from accounting profit. The HMRC service will calculate the tax due automatically.
- Submit and save the receipt. You’ll get an instant on-screen acknowledgement and reference numbers from HMRC and Companies House. Save them.
- Pay Corporation Tax. Pay any tax due by the deadline (9 months and 1 day after period end).
Common mistakes
Filing the wrong accounting period. The first one can be different from the steady-state cycle; check the dates Companies House has on file before you start.
Confusing the ARD with the tax year-end. Companies set their own ARD; it doesn’t have to be 31 March. Use what’s on your Companies House record, not the personal tax year.
Submitting accounts without the Corporation Tax computation.HMRC needs both. The accounts alone won’t close the return.
Mixing director’s loan transactions with normal P&L entries. Drawings from the company are not expenses; they sit in a director’s loan account. Mis-classifying inflates expenses and understates Corporation Tax, which HMRC will spot.
When to use an accountant
DIY filing is reasonable for a single-director Ltd with no employees, one revenue stream, sterling-only clients, and standard expenses. Beyond that the tax-planning benefits of a competent accountant generally exceed the fee. Specifically, get help if you have mixed-use assets, foreign income, employees, R&D claims, complex shareholder arrangements (multiple share classes, EMI options), large director’s loan activity, or year-end dividend planning to think about. Typical fees for a small Ltd run £500–£1,500/year for accounts and CT600; many firms offer fixed-fee packages that include monthly bookkeeping software.
What happens if you file late
Companies House issues an automatic late-filing penalty the moment the deadline passes. The scale: £150 up to one month late, £375 from one to three months, £750 from three to six months, and £1,500 beyond six months. Penalties double if you file late two years running. HMRC’s late penalties for the CT600 are separate – a flat £100 immediately, more after three and six months, and a tax-geared penalty if it’s really overdue. Persistent failure to file can ultimately lead to the company being struck off and assets reverting to the Crown.
The companies that get caught are usually the ones whose registered email and registered office are stale, so reminders never reach a human. Update both before they go wrong, not after.
Frequently asked questions
The questions directors ask most often when they’re filing their first set of accounts.
Can I file my company accounts myself without an accountant?
For a straightforward small or micro-entity company, yes. HMRC's joint filing service handles both Companies House and HMRC in one submission. If your company has employees, R&D claims, foreign income, complex shareholder arrangements, or significant director's loan activity, an accountant is worth the £500-£1,500 fee for accuracy and tax planning.
What's the difference between filing accounts at Companies House and filing a Corporation Tax return at HMRC?
Companies House gets a public-facing set of statutory accounts (balance sheet, sometimes P&L). HMRC gets a CT600 with full accounts attached and a Corporation Tax computation showing how you've arrived at taxable profit. Both come from the same underlying numbers but they're separate filings with separate deadlines.
My company hasn't traded yet. Do I still file accounts?
Yes. Dormant accounts must still be filed at Companies House annually, even if there's been no activity. They're shorter — typically just a balance sheet showing share capital. Companies House also accepts a 'dormant company accounts' form (AA02) for the simplest dormant companies.
Can I change my accounting reference date?
Yes, but with limits. You can shorten your accounting period as often as you like, but you can only extend it once every 5 years (and not by more than 18 months, or beyond 18 months from incorporation for the first period). Changing the ARD changes when accounts are due. File form AA01 to change it.
What's a 'filleted' set of accounts and should I file them?
Filleted accounts are statutory accounts with the profit and loss account and director's report removed before filing at Companies House. They're allowed for small companies and micro-entities. Most small Ltds file filleted to keep their P&L private. The full version still goes to HMRC.
How long after my company's year-end do I have to file?
9 months after the accounting reference date for subsequent accounts. 21 months from the date of incorporation for the first accounts. Corporation Tax payment is due 9 months and 1 day after the end of the accounting period. The CT600 itself is due 12 months after the end of the accounting period — but in practice everyone files at the payment date.
What are the late filing penalties at Companies House?
£150 if up to 1 month late, £375 if 1-3 months late, £750 if 3-6 months late, £1,500 if over 6 months late. Penalties double if your company files late two years in a row. HMRC charges separate penalties for late CT600.
My accounting period is different from the tax year. Is that a problem?
No — it's normal. Limited companies set their own accounting reference date, which can be any month-end. Corporation Tax accounting periods follow the company's accounting period, not the personal tax year (6 April to 5 April). Sole traders and partnerships now align with the tax year (since April 2024), but limited companies don't have to.
