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A history of the tax year and why it starts in April


The tax year in the UK starts on 6th April one year and ends on 5th April in the following year, so it’s not surprising that an accounting service will often operate around these two important days of the year. Some people may wonder why the tax year starts and ends at these times, when it may seem more logical to coincide with the calendar year. The history of the tax year can be traced back to the days of Julius Caesar.

The Roman calendar

Julius Caesar inherited a calendar that had been previously controlled by the priests at the time, who had been tasked with the determination of religious dates and the days when business could be carried out. However, the calendar had been poorly managed and it differed greatly from the seasons of the year, by a full quarter. In 46BC, Caesar added 90 days to the calendar so that the year was in alignment with the seasons. The spring equinox fell on 25th March and the start of the year was 1st January. According to Caesar, the year would consist of 365.25 days and have 12 months of either 30 or 31 days. February consisted of 28 days, with an extra day every four years.

Following the assassination of Caesar, the priests were once again in charge of the calendar and made an error when calculating the leap years. After 30 years, the successor to Caesar, Augustus, noticed the error and corrected it. However, as the Julian calendar assumed that the year had 365.25 days, it gradually became out of step with the seasons once again.

The Gregorian Calendar

Pope Gregory XIII corrected the calendar by taking 10 days out of it, placing the Spring Equinox at 20th or 21st March. However, the UK refused to make the changes to the calendar, so that it soon became even further out of step with the seasons and varied enormously from European calendars.

Changes in the UK

Almost 200 years later, the Calendar Act of 1751 decreed that 2nd September 1752 would be followed by 14th September 1752, removing days from the calendar. Following protests from the public that tax would be due for a full year due to the changes, the start of the 1753 tax year was moved to 5th April, rather than the spring equinox, allowing a full year before tax was due. In 1800, the tax year was moved to 6th April following protests when changes were introduced to stop the leap year taking place.

The tax year has remained an important date on the calendar, with many preparations needed. If you would like to discuss ways to prepare for your next 6th April, contact us for an informal chat.