You might think, logically, that the beginning of the tax year would coincide with the calendar year – and in some countries it does. In the UK, however, the scramble to get your affairs in order comes to its conclusion on 5 April, with the new tax year starting on 6 April. To understand the reason for this apparently random date, you have to go back to medieval times, says Jane Frecknall-Hughes, professor of accounting and taxation, University of Hull