Self-Assessment Late Payment Penalty Calculator
Calculate HMRC self-assessment late payment penalties. 5% surcharge at 30 days, 5% at 6 months, 5% at 12 months. Plus daily interest at Bank Rate + 2.5% from 31 January.
Self-Assessment Late Payment Penalty & Interest Calculator
Tax must be paid by 31 January. Late payment attracts 5% surcharges at three milestones, plus daily interest from the due date.
Frequently Asked Questions
What are the penalties for late payment of self-assessment?
5% of unpaid tax after 30 days. A further 5% after 6 months. A further 5% after 12 months. Plus daily HMRC interest at Bank Rate + 2.5% (currently 7.25% p.a.) from 1 February onwards.
What is the HMRC late payment interest rate in 2026?
HMRC late payment interest is Bank of England base rate + 2.5%. With base rate at 4.75%, the current rate is approximately 7.25% per annum. HMRC updates this when the Bank of England changes rates.
What is a Time to Pay arrangement?
A Time to Pay arrangement is an agreement with HMRC to pay your tax bill in instalments. It prevents the 5% surcharges applying (though interest still accrues). You can set up a plan online if you owe less than £30,000, or call HMRC on 0300 200 3822.
Can I appeal late payment surcharges?
Yes — appeal within 30 days of the penalty notice if you have a reasonable excuse (serious illness, bereavement, or an event outside your control). Interest charges cannot normally be appealed unless HMRC caused the delay.
What is payments on account?
Self-assessment taxpayers with more than £1,000 tax owed must also make two advance payments on account for the next year — due 31 January and 31 July. These are each 50% of the previous year's tax bill.
What if I genuinely cannot pay?
Contact HMRC immediately on 0300 200 3822 before the deadline to discuss a Time to Pay arrangement. Acting early significantly reduces surcharges and shows good faith. Do not wait until HMRC chases you.
Are there new penalties coming for MTD self-assessment?
Yes — Making Tax Digital for Income Tax (MTD ITSA) from April 2026 introduces a points-based late submission penalty system. Under this system, penalties only apply after accumulating multiple late submissions.
Does the 5% surcharge apply to payments on account too?
No — the 5% surcharges apply to balancing payments (the final payment due by 31 January). Payments on account attract daily interest only if paid late, not percentage surcharges.