Why does the new tax year begin on 6th April?

Guest blog by Clare’s dad, King of Trivia, Bernie Frayne.

Have you ever wondered why the new tax year begins on the 6th April; a date that is not significant in any other respect? The answer is quite interesting.

The Julian calendar was adopted by the Romans in 45 AD; it was named after Julius Caesar. The year began in January just after the winter solstice; this was when the days started to lengthen and when new growth began to appear. The Julian calendar was not quite accurate and by 1582 the difference between it and ‘solar’ time was ten day. To rectify this Pope Gregory introduced the more accurate Gregorian Calendar in Catholic countries and he brought the calendar and ‘solar’ time into alignment.

England was one of the Protestant countries that retained the Julian calendar. In the Middle Ages it was also one of the countries where the new year began on the 25th March, Lady Day, which in the church calendar is the Feast of the Annunciation. Lady Day is nine months before the birth of Jesus and it was felt that on this date Jesus began his time on earth i.e. the start of AD or Anno Domini.

All of this meant that in England the tax year began on Lady Day and that was fine until 1752 when the Julian calendar was abandoned in favour of the Gregorian equivalent. By this time the discrepancy between the two calendars had grown to 11 days, so it was decided that in 1752 the month of September in England would be shortened by 11 days. The tax year was kept at 365 days so the end of the tax year in 1753 was extended by 11 days from the 24th March to the 4th April and that was how it remained each year until 1800.

We all know that years that are exactly divisible by four are leap years and they have an extra day on the 29th February; this is particularly interesting if like Clare’s nephew John you are born on a leap year day. However if a year is exactly divisible by 100 it is only a leap year if it is also exactly divisible by 400, so the year 1600 was a leap year but not 1700 or 1800. These quite complex arrangements help to keep the Gregorian calendar year and ‘solar’ time synchronised.

The fact that the year 1800 was not a leap year in the Gregorian calendar was important because in the rejected Julian calendar it would have been. To compensate for this the end of the tax year in 1800 was extended by a day until the 5th April and it has remained so since.

It is interesting that the argument for another extension of the tax year could also have been made in 1900 but if it was put forward it was not successful. It is also interesting that the old Julian calendar has not quite died our: it is still used by the Berber people in North Africa and by the Russian Orthodox Church to calculate moveable feasts.