The following is a list of the official regnal years of the monarchs of the Kingdom of England (subsequently Great Britain and the United Kingdom), from 1066 to the present day. The regnal calendar ("nth year of the reign of King X", etc.) is used in many official British government and legal documents of historical interest, notably parliamentary statutes.
For centuries, English official public documents have been dated by the regnal years of the ruling monarch. Traditionally, parliamentary statutes are referenced by regnal year, e.g. the Occasional Conformity Act of 1711 is officially referenced as "10 Anne c.6" (read as "the sixth chapter of the statute of the parliamentary session that sat in the 10th year of the reign of Queen Anne").
Regnal years are calculated from the official date (year, month and day) of a monarch's accession. For example, King George III acceded on 25 October 1760. That marks the beginning of his first regnal year. His second regnal year starts on 25 October 1761, his third regnal year on 25 October 1762, and so on. When a monarch dies, abdicates or is deposed, the regnal year comes to an end (whether the full year has run its course or not). A new regnal year begins from a new date, with a new monarch.
As different monarchs begin their reigns at different times, the exact month and day when a regnal year begins varies across reigns. For example, Elizabeth I's regnal year starts on 17 November, James I's on 24 March, Charles I's on 27 March, and so on.
Within this article English dates before the official introduction to England of the Gregorian calendar on Thursday 14 September 1752 are given using the Julian calendar with 1 January for the start of year. However the official "legal year" — that is, the calendar used for legal, civic and ecclesiastical purposes — has not always started on the same date as the start of the historical calendar year which is 1 January (see Old Style and New Style dates). Until the 13th century, the legal year began at Christmas (25 December). From the 14th century until 1752, the 'legal' year began on 25 March. It is only since 1 January 1752, the legal year was re-set to coincide with the start of the historical calendar year (see Calendar (New Style) Act 1750).