The tax year starts on 6 April and runs through to the following 5 April. To find out why we need to go back a l o n g way.
This year is the 2000th anniversary of the death of the first Roman Emperor Augustus in AD 14. Among his many legacies was the calendar we use today.
It was initially devised by his predecessor Julius Caesar. By the time Gaius Julius came to power the Roman calendar was in a mess. One reason was that it was a secret religious document controlled by the priest class and not subject to outside scrutiny. Their job was to make the calendar work and determine the dates of religious holidays, festivals, and the days when business could and could not be conducted. But they had done it badly for many years and Caesar inherited a calendar that was out of step with the seasons by a quarter of a year.
He called in an Egyptian astronomer Sosigenes and decided to put things right. He added 90 days to the year 46 BC to bring the calendar into line with the seasons so that the spring equinox was on 25 March and the year began on 1 January as it was supposed to do. Caesar decreed that in future the calendar would follow the solar year of 365.25 days divided into twelve months of 30 or 31 days apart from the 28 day February to which would be added the leap day every fourth year.
Two years later, on the Ides of March 44 BC (15 March), Julius Caesar was assassinated on the steps of the Senate. As was their wont, the priests who were left in charge of the calendar mistook the instructions and added the extra day every third year (they counted inclusively 1-2-3-4 so to them the third year was called the fourth).
This error went unnoticed for more than thirty years and was finally corrected by Julius's successor, Augustus. By then the seventh month had been named after Julius and on Augustus's death in AD 14 the eighth month was named for him.
Apart from that one change the amended Julian calendar with the same months of the same lengths and a leap year every fourth year has run continuously since the year 8 BC.
But one small correction was needed. The Julian Calendar assumes the year is 365.25 days long - hence the extra leap day every four years. In fact the year is very slightly shorter than that. So over many centuries the calendar began to get more and more out of step with the seasons. Towards the end of the 16th century it was almost two weeks ahead of the Sun. Pope Gregory XIII decided to correct it. He took ten days out of the calendar - which fixed the spring equinox around 20/21 of March - and decreed that in future there would no Leap Year in century years unless they were also divisible by 400. Taking out three days every 400 years would almost precisely align the new Gregorian calendar with the time it takes the Earth to orbit the Sun.
The change was made in October 1582 and much of Europe soon followed. But the Protestant UK refused to obey a Papal decree and no change was made in the UK or in what were then its Colonies and Dominions. So our calendar got further out of step with the seasons and of course our dates were different from much of Europe.
It took nearly 200 years before the British Government decided to make the necessary changes. The Calendar Act of 1751 decreed that Wednesday 2 September 1752 would be followed by Thursday 14 September thus removing eleven days and bringing the calendar back where it should be. It also provided that the new year would start on 1 January. Many people had reverted to starting it on the old Roman equinox day of 25 March. You can still find eighteenth century books published early in the year with two dates such as '1724/25'.
But there was a problem. Tax was due over a year. So if there were 11 fewer days in 1752 tax would be due 11 days early. At the time the tax year began on that Roman spring equinox day, 25 March. It was called Lady Day and was one of the quarter days when rent and other payments fell due. So the Government decided that the 1753 tax year would begin eleven days later on 5 April to give the full 365 days over which tax was due.
That is still one day short of its present starting date.
That extra day was added in 1800. That year would have been a Leap Year under the old calendar but not under the new Gregorian Calendar as century years (except those divisible by 400) were no longer leap years. Again there were protests. If people were denied their extra day of 29 February then they would be paying the same taxes but over a shorter period than they expected. Once again the Government gave in and extended the tax year by a day so it ended on 5 April and the next one began on 6 April 1800. And that is where it has remained. In 1900 no-one demanded the extra day for the tax year and the question did not arise in 2000 as it was divisible by 400 and so was a leap year.
This piece is an expanded and corrected version of the Money Box newsletter for 4 April. You can subscribe to the newsletter here
5 April 2014