Tax Year

The UK Tax Year Explained

The UK tax year runs from 6 April to 5 April the following year. The current tax year is 2025/26 (6 April 2025 to 5 April 2026). This unusual start date dates back to 1752 when Britain adopted the Gregorian calendar and the Treasury adjusted the tax year to avoid losing revenue.

The tax year determines when your income is assessed, which allowances apply, and when deadlines fall. Key dates include: 6 April (new allowances begin), 31 July (second payment on account for self-assessment), 5 October (register for self-assessment), and 31 January (file return and pay any remaining tax).

Planning around the tax year end is important. Pension contributions, ISA deposits, and capital gains disposals should be timed to maximise allowances. For example, you have until 5 April each year to use your £20,000 ISA allowance — unused allowance cannot be carried forward.

How Tax Year Works in Practice

The UK tax year runs from 6 April to 5 April the following year. The current tax year (2025/26) runs from 6 April 2025 to 5 April 2026. This unusual start date has historical roots dating back to 1752 when Britain adopted the Gregorian calendar. All tax calculations, allowances, and thresholds are set per tax year.

Practical Tips

Key dates in the tax year: 6 April (new tax year, new allowances reset), 31 July (second self-assessment payment on account), 5 October (deadline to register for self-assessment for new self-employed), 31 January (self-assessment filing and payment deadline), and 5 April (ISA and pension contribution deadline for current year). Planning around the tax year end is important — use your ISA allowance and consider pension contributions before 5 April to avoid losing the current year's tax benefits.

Related Topics

Your P60 summarises your pay and tax for the tax year just ended. Your P45 is issued when you leave employment and shows your pay and tax to that date. See P60 explained and P45 explained.