Money · Penalty calculator
Self-Assessment Penalty Calculator
Calculate your exact HMRC late filing and payment penalties. Enter the tax owed and how late you are to get the precise penalty accumulating.
Instant result
Plain-English why
Copyable takeaway
What this means
No waffle. Just the number and how it was worked out.
Formula used
Filing penalty: £100 immediately, £10/day after 90 days, 5% surcharges at 6 and 12 months. Payment surcharge: 5% at 30/180/365 days.
Worked example
Filing 120 days late and paying 60 days late on a £2,000 bill: £100 + £300 (days 91-120) + £100 payment surcharge = £500 in penalties before interest.
Common questions
When does the £100 filing penalty apply?
HMRC charges £100 immediately if you miss the 31 January filing deadline, even if you have no tax to pay or your tax is less than £100.
How long before the daily penalties kick in?
If your return is more than 3 months late (around 91 days after the deadline), HMRC can charge £10 per day for up to 90 days.
Plain-English summary
The result summary for this calculator will live here.
This section translates the result into a short, direct takeaway rather than leaving the page at a bare number.
Related instruments
Keep going
Percentage Change Engine
Work out the percentage increase or decrease between two values with a clear result and worked explanation.
Open verdictVAT Engine
Add or remove VAT from a price with clear totals, tax breakdown, and net versus gross context.
Open verdictSubscription Shame Index
Find out how much your subscriptions are quietly costing you in money and attention.
Open verdict