12 and 24 month FTDs mature on the first day of the month after the fixed term ends. You can find this date on the account fact sheet.
3,6,9 and 18 month FTDs mature on the same day of the month as they were taken out. For example, a 3 month FTD taken out on 14 November will mature on 14 February.
If the month the deposit matures has less days in it than the month it started, it will mature on the last day of that month. For example, if you take a 3 month FTD out on 31 January, it will mature on 30 April as April only has 30 days in it.