Just had a chat with HSBC to try and overpay our mortgage. We do have a 10% overpayment facility which we've never used. But she let me into a secret. Our mortgage statements run from the 22nd October to the 21st October every year. She told us we can overpay by any amount we like on the 21st October because it's considered a Zero Day. Has anybody heard of this? Can't find anything about it on the Internet. So we can throw any sum of money we like at our mortgage on the 21st October and not be penalised. It used to be a bit of a secret, but they're now actively telling people to make the most of this loophole. Did anyone else know?