UK Self Assessment Late Filing & Payment Penalty Calculator

Four escalating stages under Finance Act 2009 Sch 55: (1) £100 fixed penalty the day after the deadline; (2) from 3 months late, £10 per day for up to 90 days — a further £900 maximum; (3) at 6 months late, the greater of £300 or 5% of the tax due; (4) at 12 months late, another greater-of-£300-or-5% layer, and up to 100% of the tax if HMRC find the failure deliberate and concealed.

Late payment penalties are on the unpaid balancing payment under Sch 56: 5% at 30 days unpaid, another 5% at 6 months, and another 5% at 12 months — 15% in total if the bill sits outstanding for a year. They stack on top of filing penalties and daily interest. Payments on account (31 July) attract interest but not these 5% surcharges.

From 6 April 2025 the HMRC late-payment interest rate is Bank of England base rate plus 4 percentage points (previously base + 2.5%). Interest runs from the day after the payment deadline until the tax is paid in full and is charged daily on the outstanding balance. Check the current gov.uk HMRC interest rates page for today's figure.

HMRC accept reasonable excuses such as a recent bereavement, a serious illness, an unexpected stay in hospital, a fire/flood/theft that destroyed records, postal delays outside your control, service issues with HMRC's own systems, or disability-related problems. Reasonable excuse waives filing penalties if the return is submitted without unreasonable delay once the excuse ends — it does not waive interest on unpaid tax.

Yes for the filing penalty ladder (£100 + daily + 5% + 5%), which is tied to the return not arriving. But you will still face the Sch 56 payment surcharges (5% / 5% / 5%) and daily interest on the unpaid tax. Setting up a Time to Pay arrangement with HMRC before the 30-day point usually prevents the first 5% surcharge.

Yes. The £100 initial penalty and subsequent daily/tax-geared ladder apply to the return itself — it is triggered by being late, not by owing tax. The tax-geared stages (5% at 6 and 12 months) floor at £300 each, so even a zero-tax return can still accumulate £1,600 in filing penalties after 12 months (£100 + £900 daily + £300 + £300).