In British and Irish tradition, the quarter days are the four dates in each year on which servants were hired, school terms started, and rents were due. They fell on four religious festivals roughly three months apart and close to the two solstices and two equinoxes.
The significance of quarter days is now limited, although rents for properties in England are often still due on the old English quarter days.
The quarter days have been observed at least since the Middle Ages, and they ensured that debts and unresolved lawsuits were not allowed to linger on. Accounts had to be settled, and a reckoning had to be made and publicly recorded on the quarter days.
The English quarter days (also observed in Wales and the Channel Islands) are
Lady Day (25 March, the Feast of the Annunciation);
Midsummer Day (24 June, the Feast of the Nativity of St John the Baptist);
Michaelmas Day (29 September, the Feast of St Michael and All Angels); and
Christmas Day (25 December, the Feast of the Nativity of Jesus).
Falling close to the Spring equinox, Lady Day was the first day of the civil year in England, Wales and the British dominions (but not Scotland) until 1752 (when it was harmonised with the Scottish practice of 1 January being New Year's Day). The British (personal) tax year still ends on "Old" Lady Day (5 April under the 'new style' (Gregorian) calendar, which in the 18th century corresponded to 25 March under the 'old style' Julian calendar: the Calendar (New Style) Act 1750 advanced the calendar by eleven days. 5 April is still the end of the British tax year for personal taxation.
The cross-quarter days are four holidays falling in between the quarter days: Candlemas (2 February), May Day (1 May), Lammas (1 August), and All Hallows (1 November).
At many schools, class terms would begin on the quarter days; for example, the autumn term would start on 29 September, and thus continues to be called the Michaelmas term, especially at more traditional universities.
Prior to the Christianisation of Ireland in the 5th century AD, the Celtic quarter days were observed; they are now called cross-quarter days since they fall about halfway into each of the English quarters. The names and dates of the cross-quarter days are as follows:
Candlemas (2 February) – corresponding to Imbolc (St Brigid's Day)
May Day (1 May) – corresponding to Beltane
Lammas (1 August) – corresponding to Lughnasadh
All Hallows (1 November) – corresponding to Samhain
Since 2022, when a holiday for Imbolc was added to the list, all four traditional Celtic quarter days are now marked in the Republic of Ireland by an annual public holiday on a Monday close to the quarter days.
The "Old Scottish term days" corresponded approximately to the old Celtic quarter days: