Getting started · 5 min read · Updated July 2026 · Written by the Filed Tax team

Missed the tax deadline? Here's what happens next

First, don't panic. Missing a deadline is common and completely fixable — but the penalties do grow the longer you leave it, so the one thing that helps most is acting now rather than later.

There are two separate sets of penalties: one for filing your return late, and one for paying your tax late. They stack, so it's worth understanding both.

If your return is late

The day after the deadline: an automatic £100 penalty — even if you owe no tax, or have already paid it.
3 months late: £10 a day on top, for up to 90 days — a maximum of £900.
6 months late: a further £300, or 5% of the tax due if that's higher.
12 months late: another £300 or 5%, whichever is higher.

Left a full year, that's over £1,600 in filing penalties alone before any tax — which is why catching it early matters so much.

If your payment is late

Separately, on the tax you owe:

30 days late: 5% of the unpaid tax.
6 months late: another 5%.
12 months late: another 5%.

On top of that, interest is charged daily on anything unpaid from the due date until it's cleared.

Can't pay it all at once? You may be able to set up a Time to Pay arrangement and spread the bill over instalments. It's far better to arrange this than to go quiet — HMRC is much easier to deal with when you get in touch first.

Got a good reason?

If something genuinely got in the way — illness, a bereavement, a technical failure — you can appeal the penalty on the grounds of a "reasonable excuse." It's worth doing if your circumstances fit; HMRC does cancel penalties where the reason stacks up.

The quickest way to stop the clock

The daily and percentage penalties keep building until the return is filed and the tax is paid. So the single most useful thing you can do is get it done. That's exactly the kind of catch-up job we handle all the time — send us what you've got and we'll get you straight.

Behind on a return? Let's fix it.

Catch-up filing and late returns are a big part of what we do — from £25 a month.

See pricing →

Related guides

Help with your tax return — including late and catch-up returns
Self Assessment deadlines — so it doesn't happen again
Payments on account — what else falls due in January

This guide is general information, not personal tax advice. Penalty rules can change — always confirm the current position on GOV.UK or ask us to check your situation.

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