Why does the tax year start on April 6?
The reason for the tax year running from 6 April to 5 April is primarily historical and has its origin in the switch from the Julian to the Gregorian calendar in 1752. It had been calculated in the 16th Century that the Julian calendar had lost 9 days since its introduction in 46 BC. Most of Europe changed to the new, more accurate, Gregorian calendar in 1582, but this country continued with the old one until September 1752 by which time the error had increased to 11 days. These 11 days were ‘caught up’ by being removed from the calendar altogether – 2 September was followed by 14 September. In order not to lose 11 days’ tax revenue in that tax year, though, the authorities decided to tack the missing days on at the end, which meant moving the beginning of the tax year from the 25 March, Lady Day, (which since the Middle Ages has been regarded as the beginning of the legal year) to 6 April. The dates were adopted for income tax on its re-imposition in 1842 and have not changed since.
