Uncertain why the UK Tax Year End is 5th April?
It’s a question that often comes up — why does the UK tax year end on 5th April? Why does it run from 6th April to 5th April, rather than following the calendar year like many other countries?
The answer lies not in modern finance, but in a fascinating blend of history, religion, and pragmatic policymaking that dates back several centuries. Here’s how we ended up with one of the quirkiest tax year schedules in the world.
A (Very) Brief History of the UK Tax Year end
It All Started on 25th March – Lady Day
Before 1752, the new year in England didn’t begin on 1 January. Instead, the official start of the year — including the legal and financial year — was 25th March, a date known as Lady Day.
Lady Day, which commemorates the Feast of the Annunciation, was one of four key “quarter days” in the Christian calendar. It marked the beginning of the new year for legal agreements, rent payments, and, importantly, tax collection. At the time, the tax year ran from 25th March to 24th March the following year.
The Calendar Change – From Julian to Gregorian (1752)
In 1752, the UK adopted the Gregorian calendar, replacing the older Julian calendar, which had been falling behind the solar year.
By then, the Julian calendar was 11 days out of sync. To bring the UK in line with much of Europe, Parliament declared that 2nd September 1752 would be followed by 14th September — skipping 11 days altogether.
The Treasury’s Response
This caused an immediate issue for the Treasury. If the tax year still ended on 24 March, the 1752 tax year would be 11 days shorter — meaning less tax collected.
Rather than lose revenue, the government took a practical step: it simply added 11 days to that year, pushing the end of the tax year to 4th April. A few years later, the UK Tax year end shifted again to 5th April, allowing for a consistent 365-day period.
One Final Adjustment – Leap Year 1800
Under the Julian system, 1800 would have been a leap year — but under the Gregorian calendar, it wasn’t.
To keep everything in line, the Treasury added one more day, officially setting the tax year to run from 6th April to 5th April, which remains the case today.
Why Does This Still Matter?
While it may seem like a historical footnote, the 6th April to 5th April tax year has real implications today, especially for:
- Self-assessment tax returns and deadlines
- ISA contributions and annual limits
- Pension planning and tax relief
- Capital gains calculations and planning
Understanding how and when the tax year runs can help ensure you’re making the most of your allowances — and staying compliant with HMRC requirements.
In Summary
The 5th April UK tax year end might feel unusual, but there’s solid historical reasoning behind it — driven by calendar reform and Treasury pragmatism in the 18th century.
So, while it might not be the most intuitive date in the diary, it’s not going anywhere soon — and knowing how it works can make a real difference when it comes to effective tax planning.
Let us know if you’d like help making the most of your tax year-end opportunities — whether for personal finances or your business.
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