Missed the Self Assessment deadline? What happens and what to do

If 31 January has gone and your return or your tax hasn't, you're not the first driver it's happened to. The penalties grow the longer it's left, so the most useful thing is to file and pay, or talk to HMRC, as soon as you can. Here's what GOV.UK says happens, and the ways out.

Written by Ajay Singh, a private hire driver licensed by Renfrewshire Council since January 2025 · updated 14 November 2026 · sources linked at the bottom

Two separate problems: late return and late payment

HMRC treats a late return and late tax as two different things, each with its own penalties. You can be hit by one or both.

If your return is late

GOV.UK's penalties page lists:

If your tax is paid late

You get a penalty of 5% of the tax still unpaid at 30 days, at 6 months and at 12 months, and you're charged interest on what you owe as well.

HMRC's late payment interest is the Bank of England base rate plus 4%. HMRC's interest rates page (updated 6 November 2026) gives 7.75% from 9 January 2026, and 8.00% from 24 November 2026. It changes with the base rate, so check it when you pay.

GOV.UK has a tool to estimate your penalty for a late return or payment. Penalties themselves have to be paid within 30 days of the date on the notice.

Registered late as well? If you told HMRC after 5 October and haven't paid all your tax by 31 January, you may also get a "failure to notify" penalty, based on what's still unpaid.

What to do now

1. File the return, even if you can't pay

The daily penalties start 3 months after the deadline, so getting the return in stops the late filing penalties from growing. You file late the same way as on time: online, or on paper. If you're missing a figure for the year, GOV.UK says to use your best estimate (a provisional figure), say so on the return, and correct it within 12 months.

2. Pay what you can, or set up a payment plan

If you can't pay in full, you may be able to set up a payment plan, which HMRC calls Time to Pay, to clear overdue tax in monthly instalments. GOV.UK says you'll need your Unique Taxpayer Reference, your UK bank details for a Direct Debit, and details of your income and spending. There's an online service to check if you're eligible; if you can't use it, you contact HMRC instead, and HMRC checks the plan is affordable.

Don't ignore the letters. If you don't get in touch or can't agree a plan, GOV.UK says HMRC may use a debt collection agency, take what you owe from your wages or pension, take you to court or make you bankrupt. It also says HMRC will tell you before it takes any of these steps.

3. Appeal if you had a reasonable excuse

If something genuinely stopped you, you can appeal the penalty. You usually have 30 days from the date of the penalty; miss that and you'll need to give a reason. The reasonable excuses page explains what HMRC accepts.

Stopping it happening again

Keeping records as you go makes January much easier. The free income tracker keeps fares and costs on your phone and totals them by tax year. The Self Assessment guide for drivers goes through the return step by step, and the first-year tax pack (£9.99) puts the dates and a receipts routine on paper.

For next year, you can pay towards your bill weekly or monthly with a Budget Payment Plan once you're up to date.

Questions people ask

What's the penalty for a late Self Assessment return?

GOV.UK lists an initial £100 penalty, then £10 a day after 3 months up to £900, then 5% of the tax due or £300 (whichever is greater) after 6 months, and the same again after 12 months.

What happens if I pay my tax late?

You get a penalty of 5% of the unpaid tax at 30 days, 6 months and 12 months, and interest on what you owe. HMRC's late payment interest rate is 7.75%, or 8.00% from 24 November 2026.

Can I pay my Self Assessment bill in instalments?

You may be able to set up a payment plan with HMRC to pay overdue tax monthly. GOV.UK has an online service to check if you're eligible, and HMRC checks the plan is affordable.

Can I appeal a late filing penalty?

If you have a reasonable excuse, yes. You usually have 30 days from the date of the penalty to appeal.

Sources