Why does the financial year start from 01, April

Christian Europe following the Julian calendar celebrated New Year's Day on 25 March i.e. Lady Day (to commemorate the visit of Gavriel to Myriam, informing her of Yeshua of Nazareth). Accounting practice from time immemorial also took the same view marking 25 March as the end of an accounting period. However, European scholars observed the drift in Easter (a seasonal event marking the resurrection of Yeshua) due to anomalies in the Julian Calendar. To restore and align the events associated with traditional dates, Pope Gregory XIII issued a Papal bull called Inter gravissimas ("Among the most serious") in 1582, marking Europe's switch to the Gregorian calendar.

However, the English had renounced papal authority in 1534 under the reign of Henry VIII and continued to follow the Julian calendar. In consequence, the Julian calendar by the year 1750 had lagged 11 days behind the Gregorian. The British Parliament acknowledged the practical difficulties created due to the inaccuracies of the Julain calendar and passed the Calendar (New Style) Act 1750. The Act adopted the Gregorian calendar from 1753 and elided eleven days from September 1752, thus resetting 21 March to coincide with the equinox. A vestige of the same remains in the UK's tax year, which ends on 5 April, or "Old Lady Day". The Act also rectified the start of the legal year (used for legal, financial and other civil purposes) from 25 March to 1 January, thus, restoring the Old Roman practice of beginning the year with 1 January.