Record keeping is the least glamorous part of Self Assessment and the one that matters most when HMRC asks a question. A return is only as defensible as the records behind it. This guide sets out what the main gov.uk pages require, with the retention periods that most people get wrong.
Who has to keep what
gov.uk's self-employed records page says sole traders and partners in a business partnership must keep records of business income and expenses for their Self Assessment return. Nominated partners also keep the partnership's records. You also need records of your personal income.
- If you do not prepare accounts, you record income and expenses for each tax year, 6 April to 5 April.
- If you prepare accounts, you choose your own accounting dates, though matching the tax year may make the return easier.
For non-business income, gov.uk's keeping your pay and tax records page groups the records by category: employees and company directors, savings and investments, rental income, capital gains and overseas income.
Cash basis or traditional accounting
From the 2024/25 tax year, the cash basis is the default for sole traders: you record income when you receive the money and costs when you pay the bill. Traditional accounting records income when you invoice and costs when you are billed. You must opt out of the cash basis if you want traditional accounting. The records you keep follow the method, so decide at the start of the year, not when you file. Our SA103 sole trader guide has more on the default.
How long to keep records
| Who | How long |
|---|---|
| Self-employed, partners | At least 5 years after the 31 January submission deadline for the tax year |
| Not self-employed, return filed on or before the deadline | At least 22 months after the end of the tax year |
| Not self-employed, return filed late | At least 15 months after you send the return |
| Self-employed, return filed more than 4 years late | 15 months after you send the return |
Worked examples:
- Self-employed, 2025/26. The submission deadline is 31 January 2027, so keep records until at least 31 January 2032.
- gov.uk's example. Records for the 2022/23 return, due by 31 January 2024, must be kept until at least the end of January 2029.
If you have both employment and self-employment income, apply the longer period to the business records. If in doubt, keep everything for the longer period: storage is cheaper than a failed enquiry.
What a good record looks like
HMRC can check your records to confirm you are paying the right tax. Aim for a trail from each figure on the return back to a source document.
- Income: invoices, till summaries, bank statements, platform annual reports and payslips.
- Costs: receipts, supplier invoices, mileage logs and home-use calculations.
- Banking: statements for every account used for the business, including the personal account if it mixes the two.
- Assets and loans: purchase invoices and finance agreements.
- Allowances and reliefs: gift aid receipts, pension statements and anything else you claim.
Even tiny incomes need them. If you rely on the trading allowance or property allowance, gov.uk says to keep records of the income, and that HMRC can penalise records that are inaccurate, incomplete or unreadable.
Good habits
- Separate the money. A dedicated business account makes the trail cleaner.
- Record weekly or monthly, not in January.
- Photograph receipts and store them with the date and what they were for. Check that the image is readable.
- Note the basis for any estimate, such as home-working hours or business-use proportions. See working from home expenses.
- Back them up. Digital records on a single laptop are one failure away from gone. Penalties for inaccurate or missing information are covered in the penalties guide.
- Keep going after you stop. Closing a business does not shorten the periods; our guide to stopping Self Assessment covers the final return.
Records and amendments
If you later correct a return, you need the original records to prove the change. The amending a return guide covers the 12-month window and the four-year overpayment relief claim, both of which depend on records still being available.
How ac-co helps
ac-co keeps your bank transactions and documents together and drafts your SA100 from them, so every figure on the return traces back to a source. You review the computation and approve it before it is filed. You remain responsible for keeping the underlying records for the periods above.