Have you ever wondered why the UK has a tax year that starts on the 6th of April when most major nations sensibly align their tax years with the calendar year?
To begin this tale we need to go back to 1582 when Pope Gregory XIII commanded a change from the Julian calendar (named after Julius Caesar) to the Gregorian calendar (named after himself). The old Julian calendar used to have 11 months of 30 or 31 days and a 28 or 29 day February. Although this had worked for centuries, it differed from the solar calendar by about 11.5 minutes each year so by the end of the 1500s the Julian calendar was 10 days behind the solar calendar.
However, the UK decided to ignore the Pope’s order and continued with the Julian calendar. So for the next 170 years or so there was a difference between the calendar used in the UK and the calendar used in Europe, and by 1752 the difference was 11 days.
Meanwhile, in England and Ireland the four main Christian religious holidays had been used as days on which debts, rents and accounts had to be settled. The first of these so called ‘quarter’ days fell on the 25th March and that was also New Year’s Day and the first day of the tax year.
In 1752 Britain finally realised that their calendar year needed to be aligned with the rest of Europe, moving New Year’s Day to the 1st of January and dropping the 11 days difference that had accumulated. As a result September 1752 was a bizarre month with the 2nd of September being immediately followed by the 14th of September. True to form, the British people were miffed as they had been robbed of 11 days of their lives and so decided to prowww. Not only had they been robbed of 11 days, but their taxes were not adjusted in line with the reduction in the number of days in that year. So they were expected to pay 365 days’ worth of tax for a year that only lasted 354 days.
So, to quell the unease while not conceding to the populous, the Treasury decided to extend the tax year to make it the usual 365 days in length, pushing the beginning of the new tax tear from the 25th of March to the 5th of April.
But that wasn’t the end of it. In 1800 the Treasury decided there would be another day of lost revenue since the end of the Century would have been a leap year under the Julian calendar but not under the Gregorian calendar. So 1800 was decreed a leap year for tax purposes only, which meant that the beginning of the tax year then became the 6th of April.
So, we’re stuck with the 6th of April as the first day of our tax year, but at least when this question comes up on QI, you’ll know the answer.