When does the tax year start and end? Key deadlines, historical dates and a free tax year date lookup tool.
Which Tax Year Does Your Date Fall In?
Enter any date to find out which UK tax year it belongs to, along with key deadlines for that tax year.
Current Tax Year: 2025/26
The current UK tax year is 2025/26, which runs from 6 April 2025 to 5 April 2026. All income earned, capital gains made, and pension contributions paid during this period fall within the 2025/26 tax year.
Current status: We are currently in the 2025/26 tax year. The next tax year (2026/27) begins on 6 April 2026.
Key Tax Deadlines 2025/26
6 April 2025 — Tax year 2025/26 begins. New rates, thresholds and allowances take effect.
31 May 2025 — Employers must give employees their P60 for 2024/25.
6 July 2025 — Deadline for employers to report P11D benefits in kind for 2024/25.
31 July 2025 — Second payment on account for 2024/25 due.
5 October 2025 — Deadline to register for Self Assessment for 2024/25 if not already registered.
31 October 2025 — Paper Self Assessment tax return deadline for 2024/25.
31 January 2026 — Online Self Assessment deadline for 2024/25. Payment of any tax owed for 2024/25 due. First payment on account for 2025/26 due.
5 April 2026 — Tax year 2025/26 ends.
Why Does the UK Tax Year Start on 6 April?
The unusual start date of 6 April has its roots in the 18th century. Before 1752, Britain used the Julian calendar and the tax year began on 25 March (Lady Day), one of the traditional English quarter days.
In 1752, Britain adopted the Gregorian calendar, which required skipping 11 days (2 September was followed by 14 September). The Treasury, unwilling to lose 11 days of tax revenue, moved the tax year start forward by 11 days to 5 April.
In 1800, the Gregorian calendar skipped a leap day that the Julian calendar would have included. The Treasury moved the start date forward by one more day to 6 April, where it has remained ever since.
Fun fact: The UK is one of very few countries with a tax year that doesn't align with the calendar year. Most countries use 1 January to 31 December, while Australia uses 1 July to 30 June.
Last 10 Tax Years
Tax Year
Start Date
End Date
SA Deadline (Online)
2025/26
6 April 2025
5 April 2026
31 January 2027
2024/25
6 April 2024
5 April 2025
31 January 2026
2023/24
6 April 2023
5 April 2024
31 January 2025
2022/23
6 April 2022
5 April 2023
31 January 2024
2021/22
6 April 2021
5 April 2022
31 January 2023
2020/21
6 April 2020
5 April 2021
31 January 2022
2019/20
6 April 2019
5 April 2020
31 January 2021
2018/19
6 April 2018
5 April 2019
31 January 2020
2017/18
6 April 2017
5 April 2018
31 January 2019
2016/17
6 April 2016
5 April 2017
31 January 2018
Tax Year vs Financial Year
People often confuse the tax year with the financial year, but they are different periods used for different purposes:
Period
Dates
Used For
Tax Year (Fiscal Year)
6 April - 5 April
Income tax, National Insurance, CGT, Self Assessment for individuals
Financial Year
1 April - 31 March
Corporation tax, government budgets, local authority accounting
Calendar Year
1 January - 31 December
VAT annual accounting (optional), some international reporting
Accounting Period
Varies (chosen by business)
Company accounts (max 18 months for first period)
Since April 2024: Self-employed and partnership income is now taxed on the tax year basis (6 April to 5 April), not the accounting period basis. This change was introduced by HMRC's "basis period reform" and may have affected your 2023/24 tax return with transitional overlap relief.
Self Assessment Key Dates Explained
31 January is the most important date in the tax calendar. It is the deadline for three things simultaneously:
1. Online Self Assessment return for the previous tax year (e.g. 31 January 2026 for 2024/25).
2. Payment of tax owed for the previous tax year.
3. First payment on account for the current tax year (50% of last year's bill as an advance).
31 July is the deadline for the second payment on account (another 50% advance payment). Any balancing payment or refund is settled on the following 31 January.
Late filing penalty: Miss the 31 January deadline and you face an automatic £100 penalty, even if you owe no tax. After 3 months, daily penalties of £10 per day apply (up to 90 days). After 6 and 12 months, further penalties of 5% of tax due are added.
The UK tax year starts on 6 April and ends on 5 April the following year. The current 2025/26 tax year runs from 6 April 2025 to 5 April 2026. This is different from the calendar year and from the UK financial year (which runs 1 April to 31 March).
Why does the UK tax year start on 6 April?
The 6 April start date dates back to 1752 when Britain adopted the Gregorian calendar, losing 11 days. The old tax year started on 25 March (Lady Day, a quarter day). To avoid losing 11 days of tax revenue, the Treasury moved the start date forward to 5 April, then to 6 April in 1800 when a leap year adjustment was skipped. This quirk has remained ever since.
What is the difference between a tax year and a financial year?
The UK tax year (also called the fiscal year for individuals) runs from 6 April to 5 April. The financial year runs from 1 April to 31 March and is used for corporation tax and government accounting. Most people only need to worry about the tax year (6 April to 5 April) for their personal taxes.
When is the Self Assessment deadline?
For the 2024/25 tax year, the paper Self Assessment deadline is 31 October 2025 and the online deadline is 31 January 2026. The same date (31 January 2026) is also the deadline for paying any tax owed. For 2025/26, the online deadline will be 31 January 2027.
When do I need to register for Self Assessment?
You must register for Self Assessment by 5 October following the end of the tax year in which you had untaxed income. For example, if you became self-employed during 2025/26, you must register by 5 October 2026. If you miss this deadline, you may face penalties.
What are payments on account?
Payments on account are advance payments towards your next tax bill, each equal to 50% of your previous year's tax liability. They are due on 31 January (during the tax year) and 31 July (after the tax year ends). You may need to make payments on account if your Self Assessment tax bill was £1,000 or more and less than 80% of your tax was collected at source.
Can I change my accounting year end to match the tax year?
Yes, and since April 2024, HMRC has moved to a tax year basis for self-employed and partnership income. This means your profits are now taxed based on the tax year (6 April to 5 April) rather than your accounting period. If your accounting year end doesn't align with 5 April, apportionment rules apply.
What key dates should I remember for 2025/26?
Key dates for the 2025/26 tax year: 6 April 2025 (tax year starts), 31 July 2025 (second payment on account for 2024/25 due), 5 October 2025 (register for Self Assessment for 2024/25), 31 October 2025 (paper SA return deadline for 2024/25), 31 January 2026 (online SA deadline and payment for 2024/25, plus first payment on account for 2025/26), 5 April 2026 (tax year ends).