HMRC will charge taxpayers who've filed Self Assessment tax returns late as much as £300. Back in January, the Labour Party government's tax authority imposed a January 31 Self Assessment tax return deadline.
Once missed, households were given an automatic £100 fixed penalty, followed by additional daily penalties of £10 per day for every day that a tax return is late, up to a maximum of £900.
But late filing penalties increase significantly if a Self Assessment tax return is more than three months late, because HMRC can then charge a £10 penalty for each day that the return remains outstanding.
Daily penalties from May 2026
This means daily penalties for 2024/25 tax returns will normally start to be charged from 1 May 2026. The penalties will continue for up to a maximum of 90 days if you don’t file the return – so total daily penalties could reach £900.
The Low Income tax Reform Group states: "Further late filing penalties can apply at 6 months and 12 months late (in most cases the relevant dates are 31 July 2026 and 31 January 2027 respectively) – each of these penalties will usually be the higher of £300 and 5% of the tax liability."
Avoiding the penalties
HMRC says: "To avoid this, send your Self Assessment tax return as soon as possible. All partners will be charged a penalty if a partnership tax return is late."
Myrtle Lloyd, HMRC’s Chief Customer Officer, said: “Thank you to the millions of people and agents who filed their Self Assessment tax return and paid any tax owed by 31 January.
“Anyone who missed the deadline should file their return as soon as possible, as penalties and late payment interest may be charged.
“HMRC digital channels are always the quickest and easiest way for people to sort their tax affairs. Search ‘Self Assessment’ on GOV.UK to find out more.”
