Self-assessment: planning for the January payment deadline
January's self-assessment deadline feels a long way off in October, and that is exactly why October is the month that decides whether January is calm or chaotic. Every year the same pattern repeats: the files that hurt in January are the ones where nobody chased missing records before Christmas. Planning now is not early, it is on time. What the January deadline actually demands For the 2025/26 tax year, the online filing and payment deadline is 31 January 2027. What surprises first-time filers is that the payment due is rarely just the balancing payment for the year. If your tax bill is over £1,000 and less than 80% of your tax was collected through PAYE, you also owe the first payment on account for 2026/27, which is half of the balancing payment again. So the January bill is typically 150% of the tax you thought you owed. Budget for that figure, not the smaller one. The October routine that prevents January pain Start with a one-page checklist sent to yourself, or to every...