A year behind is normal, fixable, and not the disaster it feels like at 11pm. Accountants deal with it constantly. There is a sequence that works, and it starts with something less painful than you are expecting.
What is not helpful is waiting. Penalties at Companies House and HMRC accrue automatically, on a timetable, whether or not anyone has contacted you. The cost of the backlog goes up every month you leave it.
Here is the order to do this in.
First, work out what is actually accruing
Not everything overdue costs the same. Find out where you are before you decide what to tackle first.
| What is late | What it costs |
|---|---|
| Companies House accounts (private company or LLP) — up to 1 month | £150 |
| 1–3 months | £375 |
| 3–6 months | £750 |
| Over 6 months | £1,500 |
| Corporation Tax return — 1 day late | £200 |
| 3 months late | A further £200 |
| 6 months late | HMRC issues a determination plus 10% of unpaid tax |
| 12 months late | A further 10% of unpaid tax |
| Self Assessment, old regime — immediately | £100, even with no tax to pay |
| 3 months late | £10 a day, up to 90 days — maximum £900 |
| 6 and 12 months late | 5% of tax due or £300, whichever is greater, at each point |
| Self Assessment, points-based regime | A penalty point for each late submission, then £200 once you reach the points threshold and £200 for every late submission after that |
The Companies House figures are the private company and LLP scale. Public companies are on a higher one — £750, £1,500, £3,000 and £7,500 at the same four stages. Either way the penalty doubles if you file late in two successive financial years. The CT600 figures above apply to returns with a filing date on or after 1 April 2026 — they doubled from the previous £100. And the six-month Corporation Tax determination cannot be appealed.
Check which Self Assessment regime you are in, because they are not interchangeable. The £100 / £10-a-day / 5%-or-£300 scale is the old regime. From the tax year you join Making Tax Digital for Income Tax, the points-based regime replaces it. So anyone mandated from 6 April 2026 — qualifying income over £50,000 — is already on the points system for 2026/27, while someone still outside MTD is on the old scale for the same year. From April 2027 the points regime applies to everyone filing a personal Self Assessment return. Late payment penalties are being reworked alongside it, so do not assume the old surcharges either. If you are behind, establish which side of that line you are on before you work out what the delay is costing you.
On top of all of that, HMRC charges late payment interest at 7.75%.
The point of this table is not to frighten you. It is to tell you which deadline to protect first, because the answer is usually Companies House — its penalties are the largest, entirely automatic, and there is no discretion in them.
Second, understand what you cannot argue your way out of
Companies House publishes a list of examples here, and the framing matters. It does not say these reasons are banned; it says an appeal “is unlikely to be successful if it’s based on the following examples alone”. The examples are: the company being dormant; inability to pay; financial difficulties, including bankruptcy; relying on an accountant, or your accountant being ill; another director or LLP member being responsible for preparing the accounts; these being your first accounts; being unfamiliar with the filing requirements; postal delays; and directors living or travelling overseas.
Knowing this early saves you weeks of drafting an appeal that will not land on its own. Put the energy into filing instead.
Third, gather the raw material
You need less than you think. Almost everything can be rebuilt from bank data.
The essentials:
- Bank statements for every business account, covering the whole period — download as CSV, not PDF, if your bank offers it
- Business credit card statements
- Sales invoices you issued, or the reports from whatever raised them
- Purchase invoices and receipts, in whatever state they are in
- Payroll records if you have employees
- Loan and finance agreements
- Your previous year’s accounts or tax return, for opening balances
- Stock figures at the year end, if you hold stock
Do not stop to organise these into folders. Get them into one place and let the software or your accountant sort them.
Fourth, work forwards, not backwards
The instinct is to start with the most urgent deadline. That is the wrong end.
Bookkeeping is cumulative. Opening balances feed the next period, and reconstructing March before you have done January produces figures you will redo. Start at the earliest unreconciled month and work forwards in order.
The sequence:
- Import the bank data for the whole backlog period in one go
- Reconcile month one completely — every line categorised, nothing left unexplained
- Match receipts and invoices to those transactions as you go
- Flag anything you genuinely cannot identify in a single list rather than stopping
- Repeat, month by month, in order
- Deal with the flagged list at the end, when patterns from later months often explain earlier entries
- Apply year-end adjustments — accruals, prepayments, depreciation, capital allowances, stock
- File in deadline order, starting with whatever is generating the largest penalty
Step four is the one that saves the most time. A single unexplained £340 payment can cost you forty minutes if you chase it in the moment, and thirty seconds if you recognise it in September.
What to do about missing records
This is the fear that stops people starting, and GOV.UK is more accommodating than most people expect.
If you run a limited company and cannot replace records that were lost, stolen or destroyed, you must do your best to recreate them, tell your Corporation Tax office straight away, and include that information in your Company Tax Return.
If you are self-employed and cannot replace them, you must do your best to provide figures and tell HMRC when you file whether you are using estimated figures (your best guess where actual figures are not available) or provisional figures (temporary estimates while you wait for the real ones, which you must then submit).
Estimated and provisional figures are a recognised part of the system. Filing something reasonable and disclosed beats filing nothing.
What catching up costs
Providers price backlog work separately from current-year work, and the published rates give you a benchmark.
| Provider | Catch-up price | Basis |
|---|---|---|
| Sleek | £750 per financial year | Backdated bookkeeping, up to 100 transactions |
| Osome | £850 per year | Historical filing and bookkeeping |
Both verified from provider pricing pages on 21 August 2026. Expect a premium above these where transaction volume is high, records are fragmentary, or multiple years are involved.
Set that against the penalty position. A single set of company accounts six months overdue is a £1,500 Companies House penalty on its own, before HMRC. In most backlog cases the fee is smaller than the penalties still accruing.
Do not stop filing current work to catch up
The common mistake is pausing everything to fix history. Do not. Current deadlines keep running and generate fresh penalties on top of the old ones.
If you are within Making Tax Digital for Income Tax — sole traders and landlords with qualifying income over £50,000 were mandated from 6 April 2026 — quarterly updates are due 7 August, 7 November, 7 February and 7 May. There is a grace period for 2026/27 with no penalty points for late quarterly updates, but the digital record-keeping obligation stands and late return and late payment penalties still apply.
Run catch-up alongside current compliance, not instead of it.
If you cannot pay what the catch-up reveals
Filing and paying are separate obligations, and filing late costs more than paying late in most cases. File first.
If a tax bill lands that you cannot meet, HMRC’s online Time to Pay service is available where you owe £30,000 or less, you are up to date with your returns, and you have no other tax debts or payment plans in place. Setting up an arrangement before the debt is chased is materially better than after.
Frequently asked questions
How far behind on bookkeeping can I get before it is a real problem?
The moment a filing deadline passes. Companies House penalties are automatic and start at £150, and a Corporation Tax return one day late costs £200 for returns with a filing date on or after 1 April 2026. Bookkeeping itself has no deadline, but everything it feeds does.
Can I catch up a year of bookkeeping myself?
Yes, if the volume is manageable and you work forwards from the earliest unreconciled month. Import the whole period’s bank data at once, reconcile month by month in order, and keep a single list of unidentified transactions to resolve at the end rather than stopping each time.
What if I have lost my receipts?
GOV.UK expects you to do your best to recreate the records and tell HMRC. Companies must notify their Corporation Tax office straight away and include the information in the Company Tax Return. Self-employed people can file using estimated figures, or provisional figures which are updated once actual figures are available.
How much does it cost to get a bookkeeping backlog cleared?
Published catch-up pricing in August 2026 ran at £750 per financial year at Sleek for up to 100 transactions and £850 a year at Osome for historical filing and bookkeeping. Expect more where volume is high or records are incomplete. Compare that against the penalties already accruing before deciding it is expensive.
Should I file late accounts even though I will be penalised?
Yes. Companies House penalties increase with delay — for a private company or LLP, £150 up to a month, rising to £1,500 beyond six months, with a higher scale of £750 to £7,500 for public companies — and they double if you file late in two successive years. The penalty is already fixed by how late you are; leaving it longer only makes it larger.
Getting a backlog cleared without the drama
SmartFiling clears bookkeeping backlogs on flexible plans — bank data reconstructed, months reconciled in order, and everything brought up to a point where your filings can go in. Send us what you have, in whatever state it is in. We work with Xero, QuickBooks, FreeAgent, Sage and Dext.
Fixed fees agreed upfront so you know the cost before we start. Fully online, no phone calls required, and no judgement about how you got here.
SmartFiling is the trading name of Ballards Newman (Finchley) Limited, an ICAEW-regulated London practice with over twenty years of UK tax and compliance experience.
