In British and Irish tradition, the quarter days were the four dates on which servants were hired, and rents and rates were due. They fell on four religious festivals roughly three months apart.

The English quarter days (also observed in Wales) are:

• Lady Day (March 25)
• Midsummer Day (June 24)
• Michaelmas (September 29)
• Christmas (December 25)

Lady Day was also the first day of the year in the British Empire until 1752. The British tax year still starts on 'Old' Lady Day (6 April under the Gregorian calendar corresponded to 25 March under the Julian calendar).

The Irish quarter days were observed on the same days as in England. They are no longer generally observed.

The Scottish quarter days are:

• Candlemas (February 2)
• Whitsunday (May 15)
• Lammas (August 1)
• Martinmas (November 11).

The Terms & Quarter Day (Scotland) Act 1990 redefined these dates, at least in official use, as the 28th day of February, May, August and November respectively.

The significance of quarter days is now limited, although leasehold payments and rents for business premises in England are often still due on the old English quarter days.

The cross-quarter days derive from the Celtic calendar. They are Candlemas, May Day (May 1), Lammas, and All Hallows (November 1).