Have you ever wondered why the tax year runs from 6^th April to 5^th April? It is odd that it doesn’t follow the regular calendar year (starting on 1^st Jan) like most other things. But why is this?

The story is somewhat confusing as it involves The Virgin Mary, Julius Caesar and Pope Gregory VIII. But we are going to attempt to simplify it…

So, to begin with the tax year used to run from 25^th March to the 24^th March and this was because the 25^th March was Lady Day – 9 months before Jesus was born. Easy enough to follow so far. 

At this time the Julian Calendar was being used and there were 365.25 days a year (increasing to 366 every four years i.e. every leap year).  However, this was inaccurate, as a year was actually 11 minutes shorter than assumed. It’s getting a bit tricky now.

To fix this, the Gregorian Calendar was introduced by Pope Gregory VIII in 1582 which said that only if the year was divisible by 400 will it be a leap year, making a year 365.2425 days long. 

The UK was a bit slow to catch up (taking nearly 200 years) and because of the delay, they were 11 days out of sync. And to fix this, they just skipped 11 days (making Wednesday 2^nd September being followed by Thursday 14^thSeptember). But they also didn’t want to miss out on tax, so they added 11 days onto 24^th March, making the tax year end on 4^th April.

Then comes the year 1800, which was supposed to be a leap year according to the Julian Calendar but not to the Gregorian Calendar (it wasn’t divisible by 400). Again, not wanting to miss out on any tax, the UK added an extra day making the tax year end on 5^th April instead. That wasn’t too hard to follow…