To avoid the January 31 deadline rush and penalties, file your self-assessment tax return early. First-timers must register with HMRC for a Unique Taxpayer Reference, which can take up to 15 days. Filing late incurs a £100 penalty, with additional daily fines and interest on late payments, which can increase costs significantly over time.
Help is available to spread payments through a Time to Pay arrangement, allowing affordable monthly installments to be set up online for debts under £30,000. For larger amounts, taxpayers must contact HMRC directly.
If you’re unsure whether you need to file a Self Assessment tax return, check on the gov.uk website: Check if you need to send a Self Assessment tax return – GOV.UK.
Ahead of the January 31, 2026 deadline, BDO tax partner Elsa Littlewood commented:
“With the self-assessment deadline approaching, there’s still time to prioritise filing—especially for those who missed submitting returns between Christmas Eve and Boxing Day, or those yet to complete theirs.”