What are the dates for the 2025-26 tax year?

The UK tax year 2025/26 runs from 6 April 2025 to 5 April 2026. This 364-day year deliberately does not follow the standard January-December calendar.

Unlike most countries, the UK tax year begins on 6 April and ends on 5 April of the following year. The 2025/26 tax year starts 6 April 2025 and ends 5 April 2026.

The Key Dates for 2025/26 at a Glance

• 6 April 2025 – Start of 2025/26 tax year; new personal tax allowance and thresholds take effect
• 6 April 2025 – New state pension rates and benefits increase (in line with September CPI)
• 31 July 2025 – Second payment on account for 2024/25 tax year due
• 31 October 2025 – Paper Self Assessment return deadline for 2024/25 year
• 31 January 2026 – Online Self Assessment return for 2024/25 + first payment on account for 2025/26
• 5 April 2026 – End of 2025/26 tax year
• 31 October 2026 – Paper return deadline for 2025/26
• 31 January 2027 – Online return + balancing payment deadline for 2025/26

Why 6 April to 5 April?

The tax year dates originate from the calendar reform of 1752. When Britain adopted the Gregorian calendar (dropping 11 days in September 1752), the financial new year was pushed to 6 April to avoid a short tax year and revenue disruption. The start date briefly shifted to 5 April in 1900 but 6 April became permanent in 1909.

How the Tax Year Affects PAYE

For employees, PAYE operates entirely within these tax year boundaries. Your employer runs payroll using tax codes issued by HMRC for the current tax year. At the end of the tax year (5 April), your employer must provide a P60 – a certificate of your earnings and tax deducted. Your tax code then resets on 6 April.

Personal Allowance and Tax Thresholds for 2025/26

• Personal Allowance: GBP 12,570 (frozen until April 2028 per Autumn Budget 2025)
• Basic rate band: GBP 12,571 – GBP 50,270 (20%)
• Higher rate band: GBP 50,271 – GBP 125,140 (40%)
• Additional rate: Above GBP 125,140 (45%)
• NIC Primary Threshold: GBP 12,570 per year for employees

Self-Assessment and the Tax Year

Self Assessment returns always relate to the tax year that ended on 5 April. The 2025/26 return filed by 31 January 2027 captures all income from 6 April 2025 to 5 April 2026 – employment, self-employment profits, property income, savings interest, dividends, and capital gains.

Why This Matters for Financial Planning

Because the UK tax year runs April to April, tax planning windows (ISA allowances, pension contributions, business expense claims) follow this cycle. A pension contribution paid by 5 April 2026 reduces your 2025/26 tax liability – it must be actually paid by that date, not merely pledged.