The last moment an obligation can be met — and it does not always move off a weekend.
A deadline is the last moment by which something must be done. In operational time the interesting question is never what the date is but what happens when it lands awkwardly.
Most people assume a deadline falling on a Saturday moves to the Monday. Frequently it does. Frequently it does not, and the difference is set by the instrument rather than by convention — so the same calendar date can be a hard stop in one country and a soft one next door.
That is why the corpus stores a shift rule beside every deadline rather than a date. A date alone cannot tell you whether it will move, and by the time you find out it has not, the deadline has passed.
The same shape of obligation in two countries, both landing on a non-working day, behaving in opposite ways. One moves and one does not.
| 🇬🇧 | Sunday 31 January 2027United Kingdom | Self Assessment online returnFalls on a Sunday and does NOT move. The shift rule is none — the deadline stands. |
| 🇩🇪 | Saturday 31 July 2027Germany | EinkommensteuererklärungFalls on a Saturday and DOES move, to Monday 2 August, under a next-working-day rule. |
| 🇯🇵 | Monday 15 March 2027Japan | Kakutei shinkokuA weekday in 2027, and carries the same next-working-day rule for the years it is not. |
Frequently the same thing. Where they differ, a due date is when an obligation arises and a deadline is when failing it has consequences — the grace period sits between.
A deadline is a date. A cut-off is a time of day, after which work is carried to the next business day.
See also due date · filing deadline · grace period · roll convention · cut off time
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