On this page
In short
- The UK tax year runs 6 April to 5 April.
- Your Personal Allowance, tax bands and expenses claims all reset with it.
- The oldest year you can claim for drops off every 5 April.
- Self Assessment deadlines: register by 5 October, file online by 31 January.
Why 6 April
A historical quirk from the calendar change of 1752 and the old Lady Day quarter. It has stayed because everything in payroll is built around it.
The dates that matter
| Date | What happens |
|---|---|
| 5 April | Tax year ends. Oldest claimable year drops off |
| 6 April | New year, new codes, new bands |
| 31 May | Employers must issue P60s |
| 6 July | P11Ds issued for benefits |
| 5 October | Register for Self Assessment if you need to |
| 31 January | Online Self Assessment return and payment due |
What it means for a rebate
Each tax year is a separate claim with its own figures. A claim started in March covers 4 full years plus the current one; the same claim in May has lost the oldest. How far back you can claim.
Questions
Which year does my March payslip belong to?
The tax year ending 5 April. Payday date decides, not the work period.
When does HMRC send P800s?
Between June and March after the year ends.
Not ready to claim today?We'll email you this guide and one reminder before the 5 April deadline, when the oldest tax year drops off. Nothing else.
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This guide is general information, not advice about your circumstances. Figures use HMRC rates for the 2026 to 2027 tax year. We are a paid tax agent and not HMRC.
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