Guides › Missed the 31 January Deadline? Penalties and Next Steps

Missed the 31 January Deadline? Penalties and Next Steps

Short answer: Per GOV.UK, you get a penalty if you send your return late or pay late. File and pay as soon as you can, because penalties and interest build up. You can use GOV.UK's official calculator for an estimate.

Late filing penalties (GOV.UK)

• £100 initial penalty.
• After 3 months: additional daily penalties of £10 a day, up to a maximum of £900.
• After 6 months: a further penalty of 5% of the tax due or £300, whichever is greater.
• After 12 months: another 5% or £300, whichever is greater.

For a deadline of 31 January 2027, three months after is, on our reading, around 1 May 2027. That is our calculation, not GOV.UK wording: confirm with the official calculator.

Late payment penalties (GOV.UK)

• 5% of the unpaid tax at 30 days, 6 months and 12 months, plus interest on the amount owed.
• If you register after 5 October and do not pay all of your bill by 31 January, you may get a "failure to notify" penalty based on the amount still left to pay.

What to do

1. File the return now if you haven't. The penalty clock for filing stops growing once HMRC receives it.
2. Pay what you owe, or contact HMRC about a payment plan if you cannot pay in full (see difficulties paying); GOV.UK says HMRC checks whether a plan is affordable.
3. Check the penalty: use the official estimator. GOV.UK says it does not take account of payments you've already made, earlier penalties or interest, or credits, and says not to use it in some cases (for example if you got your request to file less than 3 months before the deadline).
4. Pay a penalty within 30 days of the date on the penalty notice.
5. Appeal if you have a reasonable excuse.

Interest

Interest is charged on late payments. We do not quote a rate here because it changes: check GOV.UK's interest rates page.

FAQ

Is the £100 charged even if I owe nothing? GOV.UK says you get a penalty if you need to complete a return and send it late; it doesn't say the penalty depends on owing tax. Check with HMRC for your case.

Can I appeal? Yes, if you have a reasonable excuse.

Is our estimate official? No.

What we could not verify

• The current interest rate on late tax.
• What counts as a reasonable excuse in your case (see GOV.UK's appeals guidance).
• Our in-browser penalty estimator gives a rough figure; use GOV.UK's official estimator for the number that counts.

Sources (GOV.UK)

• GOV.UK, Self Assessment tax returns: Penalties — https://www.gov.uk/self-assessment-tax-returns/penalties (read 17 October 2026)
• GOV.UK, Estimate your penalty for late Self Assessment tax returns and payments — https://www.gov.uk/estimate-self-assessment-penalties (read 17 October 2026)
• GOV.UK, Difficulties paying HMRC — https://www.gov.uk/difficulties-paying-hmrc (read 17 October 2026)
• GOV.UK, Self Assessment tax returns: Deadlines — https://www.gov.uk/self-assessment-tax-returns/deadlines (read 17 October 2026)

Deadlines calendar → Penalty estimator →

Not tax advice. See the disclosure.