Self Assessment penalties
Two meters run when a return is late: one on the return itself, one on the unpaid tax, and they add up. The filing meter does not care whether anything is owed, a year late with a nil bill still costs £1,600. Set the tax, slide the lateness, and the steps land where the statute puts them.
Where the steps land
already charged at this lateness still ahead
Penalty amounts effective 6 April 2011, SI 2011/702; verified unchanged against gov.uk on 18 July 2026.
These are the fixed steps of the classic regime, for anyone not yet inside Making Tax Digital for Income Tax. The points-based regime already applies inside MTD from April 2026, and the government has announced its extension to all Self Assessment taxpayers from April 2027. The statutory clocks run in calendar months from the filing and payment dates; the slider counts days, so a boundary can sit a day or two either side of the real one. The figures assume the online deadline; a paper return runs from 31 October instead.
The daily penalties technically need an HMRC decision and a notice, Sch 55 para 4; for Self Assessment they are charged as a matter of routine. Where HMRC finds the return deliberately withheld, the twelve-month step rises to 70 or 100 per cent of the tax, para 6. The 5 per cent payment charges bite on the balancing payment; a late payment on account collects interest but not these penalties.
Interest runs separately on unpaid tax from the due date, at a rate tied to the Bank of England base rate; it is not in these figures. Whether HMRC accepts a reasonable excuse, allows a special reduction or finds the withholding deliberate is decided case by case, and none of it is arithmetic. How we check these numbers.