Answers · UK 2025/26
When does the UK tax year start and end?
The UK tax year runs from 6 April to 5 April. Originally based on the old Julian calendar quarter day (Lady Day, 25 March) plus 11 days lost in the 1752 Gregorian calendar switch. So 2025/26 = 6 April 2025 to 5 April 2026.
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UK tax year 2025/26 dates and history. Start: 6 April 2025. End: 5 April 2026. References: "tax year 2025/26", "2025 to 2026 tax year", "April 2025 to April 2026" all mean the same period. Historical origin: derived from "Lady Day" (25 March, an old quarter day in English finance going back to medieval times). When Britain adopted the Gregorian calendar in 1752, 11 days were "lost" — Treasury insisted on keeping the same length of tax year, so quarter day moved to 5 April. Then in 1800 another day was added (centuries leap year discrepancy between Julian and Gregorian) — making 6 April the start date that has held since. Key dates within tax year 2025/26: 6 April 2025 — new rates take effect (NLW, NI thresholds, etc.); 31 July 2025 — second Payment on Account for 2024/25; 5 October 2025 — register for SA if newly self-employed; 31 October 2026 — paper SA filing deadline for 2025/26; 31 January 2027 — online SA filing + balancing payment + first PoA for 2026/27. Why not align with calendar year: changing it would be a massive logistical exercise across PAYE, pensions, benefits — has been proposed (OTS in 2021) but rejected on cost grounds. Other countries: most align with calendar year; UK's anomaly continues. For company accounting periods: typically 12 months, can be set to align with calendar year — Corporation Tax follows the accounting period.
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This answer is informational only and does not constitute financial, tax or legal advice. Figures are for the 2025/26 UK tax year. See our methodology and sources.