Deadlines and admin

Self Assessment late filing and late payment penalties

Two separate clocks run from 31 January: one for the return, one for the money, and each has its own charges.

A return filed 120 days late on a bill of £3,000, paid on the same day, costs £540 in penalties under the current Self Assessment rules: £100 straight away, £290 of daily penalties and £150 for paying late, with interest on top. The filing side starts with a fixed £100 the day after the deadline, whatever you owe. After 3 months HMRC adds £10 a day, capped at £900. At six months comes 5 % of the tax due or £300, whichever is greater, and the same again at twelve months. The payment side charges 5 % of the unpaid tax at 30 days, six months and twelve months. These rules stop applying to you from the tax year you join Making Tax Digital. Enter your own delays below.

Self Assessment late filing and payment penalties

Penalties in total

£540

Late filing, initial£100
Daily penalties£290
6 and 12 month penalties£0
Late payment (5 % steps)£150

Rules for returns outside Making Tax Digital. Interest is added on late tax.

See the 2026/27 deadlines

Figures checked by Radif Partners · Editorial policy · How we calculate

How the charges build up over a year

The table follows one sole trader, a hairdresser with £2,000 of tax to pay, who files the return and pays the bill on the same day, later and later after 31 January. Interest is left out because it depends on the base rate at the time.

Tax due £2,000, current Self Assessment rules (outside Making Tax Digital).
Return and payment late byFiling penaltiesPayment penaltiesTotal
1 day£100£0£100
45 days£100£100£200
100 days£190£100£290
200 days£1,300£200£1,500
400 days£1,600£300£1,900

Two things stand out. The fixed charges dominate at this size of bill: the £100, the £900 of daily penalties and the minimum £300 amounts are the same for a bill of £2,000 as for no bill at all. And the percentage charges overtake them once the tax is larger. With £15,000 to pay and both the return and the money 200 days late, the total reaches £3,250, because 5 % of £15,000 is more than the £300 floor.

The filing clock

It starts the day after the deadline for the type of return you send: 31 October 2026 for paper and 31 January 2027 online for the 2025/26 year. The £100 is automatic. After 3 months the daily charge of £10 applies for up to 90 days, which is where the £900 ceiling comes from. At six months HMRC adds the greater of £300 and 5 % of the tax due, and at twelve months it does the same again (GOV.UK, Self Assessment penalties). In a partnership, a late partnership return means a penalty for each partner.

The payment clock

Unpaid tax is charged 5 % at 30 days, again at six months and again at twelve months, each time on the amount still unpaid. Separately, late payment interest runs from the first day at the Bank of England base rate plus 4 % (HMRC interest rates). Because the base rate moves, the rate on your debt can change while it is outstanding.

Registering late is a third risk

If you told HMRC after 5 October that you needed a return and did not pay the whole bill by 31 January, a failure to notify penalty may follow, based on the amount still unpaid. HMRC issues it within 12 months of receiving the return.

When Making Tax Digital takes over

From the tax year you join Making Tax Digital for Income Tax, a points system replaces the £100 and daily penalties, and a new late payment penalty replaces the 5 % steps. Interest is unchanged. The switch is by tax year: a sole trader brought in on 6 April 2026 is still under the old rules for the 2025/26 return due 31 January 2027. HMRC’s guidance also states that from April 2027 the new penalties will apply to everyone who sends a personal Self Assessment return, so the regime on this page is in its last years (HMRC, MTD penalties).

The two systems weigh differently. On £3,000 paid 45 days late, the current rules charge £150. Under Making Tax Digital the same delay in 2026/27 costs £192: 3 % at day 15, 3 % at day 30, then a yearly 10 % charged daily. Shorter delays are where the new system bites harder, except in the first year. Paid 20 days late, the bill attracts nothing under the old rules, £90 under the new ones in a normal year, and £0 in your first year, when the grace period is 30 days rather than 15. For 2027/28 the two fixed steps rise to 4 % each. Late returns earn a point each, and a £200 penalty arrives only at 4 points. The MTD penalties page has a calculator for the new regime, and the MTD checker tells you which year you join.

Questions sole traders ask

Do I get a late filing penalty if I owe no tax?

Yes. The first £100 is charged for a late return whatever the bill. The daily penalties do not depend on the tax either, and the six-month charge has a floor of £300. A return with nothing to pay that arrives 200 days late therefore costs £1,300. Late payment penalties, by contrast, are a share of unpaid tax, so they are nil.

How much is the fine if my tax return is ten days late?

£100 for the return, and no late payment penalty yet if the money also goes in within 30 days: on a bill of £800 paid ten days late the total is £100. Interest runs on the unpaid £800 from the due date. The daily charges only begin after 3 months.

Can I appeal a self assessment penalty?

Yes, if you had a reasonable excuse for missing the deadline. The penalty notice explains the route. A penalty you do not appeal must be paid within 30 days of the date on the notice. A £100 filing penalty does not go away just because the return is sent afterwards, so sending it quickly limits the damage rather than undoing it.

Do the old £100 late filing penalties still apply after I join MTD?

Not to the tax years you are in Making Tax Digital. From that year a late return earns a penalty point, and a fixed £200 only once you hold 4 points. Earlier years keep the old rules: in MTD from 6 April 2026, your 2025/26 return due 31 January 2027 is still covered by the £100 regime.

Work out the next thing

Self Assessment deadlines

Every Self Assessment date for 2025/26 and 2026/27, from 5 October to 31 July, and what MTD adds.

MTD penalties

Late submission points, the fixed penalty at the threshold and the sliding late payment charge.

Payments on account

The two advance payments of 31 January and 31 July, and the balancing payment.

Making Tax Digital checker

Your MTD for Income Tax start date from turnover and rents, year by year, with exemptions and letters.

Official sources behind this page

Worked out by

Independent publisher of UK self-employed tax calculators for 2026/27

Rates checked on · Editorial policy · Contact

Tax year 2026/27 (6 April 2026 to 5 April 2027), HMRC and GOV.UK pages last read on . Estimates only, from published 2026/27 rates; not tax advice. HMRC’s calculation of your return is the one that counts.