What is the penalty for filing a Self Assessment return late?

Short answer

One day late costs £100 automatically, even if you owe nothing. From three months, £10 a day runs for up to 90 days. At six and twelve months HMRC adds the greater of 5% of the tax or £300 each time — at least £1,600 for a return over a year late.

The Self Assessment penalty regime in Schedule 55 of the Finance Act 2009 is automatic. There is no warning letter and no discretion, and the first two rungs do not depend on owing any tax at all — a nil return filed late still collects them, and being due a refund makes no difference.

The late filing ladder

1 day late — £100 fixed penalty.
3 months late — £10 a day for up to 90 days, a maximum of £900.
6 months late — the greater of 5% of the tax due or £300.
12 months late — the greater of 5% or £300 again, rising to 70% or even 100% of the tax where HMRC decides information was deliberately withheld and concealed.

A return filed just over a year late therefore costs at least £1,600 in filing penalties before any tax is counted. Partnership returns are harsher still: the fixed penalties are charged on every partner individually.

Late payment is penalised separately

Paying late runs on its own ladder under Schedule 56: 5% of the tax still unpaid at 30 days, another 5% at six months, and another 5% at twelve. Daily interest runs from the day after the due date at the Bank of England base rate plus four percentage points. Those 5% charges apply to the balancing payment, not to payments on account — miss a 31 July instalment and you accrue interest but no percentage penalty.

The single most valuable move if you cannot pay is a Time to Pay arrangement agreed before the next penalty trigger date: keep to it and the 5% charges that would have fallen due are not applied. Interest still runs. For Self Assessment debts of £30,000 or less you can usually set instalments up online within 60 days of the deadline, provided the return is filed.

You have 30 days from a penalty notice to appeal, online or on form SA370, on the ground of reasonable excuse — bereavement, serious illness, fire or flood, or an HMRC systems failure. Insufficient funds, finding the software difficult, and not getting a reminder do not qualify, and relying on an accountant who failed to file is rarely enough on its own. File the outstanding return before you appeal: an unfiled return sinks almost any excuse, and the daily penalties keep running while you argue.

Read the full guide: Self Assessment Late Filing and Payment PenaltiesCovers eligibility, the process, deadlines, and next steps in depth.

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