In short
- Register by 5 October after the end of the tax year if you have never filed before.
- File and pay by 31 January after the end of the tax year (online filing).
- Do not wait until January: gather your records early.
Key dates for the 2025 to 2026 tax year
| What | Deadline |
|---|---|
| Tell HMRC you need to file (if you have not filed before) | 5 October 2026 |
| Paper tax return received by HMRC | 31 October 2026 |
| Online tax return submitted | 31 January 2027 |
| Pay your Self Assessment tax | 31 January 2027 |
| Second payment on account | 31 July |
Each later tax year follows the same pattern, one year on. If you have to use MTD for Income Tax, you also send quarterly updates during the year, and your 2026 to 2027 tax return is sent from your MTD software by 31 January 2028. See the MTD guide.
Income and the £1,000 trading allowance
If your trading income in a tax year is £1,000 or less, you may not need to report it. If it is higher, you can either claim the £1,000 trading allowance or deduct your actual business expenses. You cannot claim both.
Records checklist
- Sales invoices and a record of all income received
- Bank and credit card statements for the year
- Receipts and invoices for business expenses
- Mileage logs if you use your vehicle for business
- Household bills if you claim for working from home
- Stock records, if you buy goods to sell
- Details of equipment bought during the year (these are usually claimed through capital allowances)
Cash basis or traditional accounting?
With the cash basis, you record income when you receive it and expenses when you pay them. With traditional accounting, you record them when you invoice or are billed. The method you use affects how your figures are worked out, so it is worth choosing deliberately.
How long to keep records
Keep your Self Assessment records for at least five years after the 31 January submission deadline. VAT records must be kept for six years. You can keep records on paper, in a spreadsheet or in accounting software.
If you would like your books ready well before the January rush, see services and fees.
This guide is general information, not personalised tax advice. Rules, thresholds and dates can change, so check GOV.UK or get advice on your own circumstances.