When the year starts 📆
I notice a few people mentioning the arbitrariness the first day of the year. It's true, there's no magic to new year's day. The year could begin on Christmas day (a quarter day) or on the shortest day (solstice). But there's a given day for letting off fireworks and wishing people happiness, and it's 1 Jan.
But that's only the start of the calendar year. There's the academic year that begins at Michaelmas (29 Sep). The start of the year for legal contracts, particularly in farming, was Lady Day (25 Mar). I read an entertaining book by a man who was a farm labourer before WW2. He was contracted to a farmer for a year from Lady Day, as were all the other labourers. He described the subtle negotiations between him and the farmer as the date approached. Usually neither of them wanted to move, so the only issue was pay. But the only way to bargain was to make the other half-believe that the contract wouldn't be renewed. The book described a lot of hint-dropping and almost no direct discussion.
I've read that Lady Day used to count as New Year's Day, but I've also read that the Tudors gave presents on 1 Jan, so they just had as many New Year's Day as they liked.
I once worked for the property arm of a pension fund. Rents for commercial leases were due "quarterly on the usual quarter days" which sounds innocuous enough, but one of those is Christmas Day, a bank holiday. The rent is due on a day it can't be paid!