When Does the UK Tax Year Start and End?
The UK tax year runs from 6 April to 5 April the following year. The 2025/26 tax year therefore runs from 6 April 2025 to 5 April 2026. This unusual start date dates back to the calendar reform of 1752 and has remained unchanged since.
For freelancers and the self-employed, the tax year defines which income and expenses belong to which return. Income earned on 5 April 2026 goes into the 2025/26 return; income earned on 6 April 2026 belongs to 2026/27.
Key Tax Dates for 2025/26
| Date | What Happens |
|---|---|
| 6 April 2025 | 2025/26 tax year begins |
| 5 October 2025 | Deadline to register for Self Assessment (if newly self-employed in 2024/25) |
| 31 October 2025 | Deadline for paper Self Assessment return for 2024/25 |
| 31 January 2026 | Deadline to file 2024/25 online return AND pay tax owed |
| 31 January 2026 | First payment on account for 2025/26 due |
| 31 July 2026 | Second payment on account for 2025/26 due |
| 5 April 2026 | 2025/26 tax year ends |
What Changes Each April?
The start of a new tax year typically brings changes to tax rates, thresholds and allowances. These are announced in the Budget and confirmed in legislation. Common changes include adjustments to the personal allowance, NI thresholds, pension annual allowance, dividend allowance and the higher-rate income tax band. For 2025/26 the main figures are unchanged from 2024/25 โ most thresholds were frozen in the Autumn 2022 statement and remain frozen through 2028.
Payments on Account Explained
If your Self Assessment tax bill exceeds ยฃ1,000, HMRC requires you to make payments on account โ advance payments towards next year's liability. Each payment is 50% of the previous year's bill. Payment 1 is due 31 January (at the same time as the final payment for the previous year) and payment 2 is due 31 July. In year two of self-employment, this means your January payment covers: the previous year's balance plus a full payment on account โ potentially 150% of your first year's bill.