Can't pay your Self Assessment bill by 31 January 2027?

If you are looking at your 2025/26 Self Assessment bill and know you can't pay it all by 31 January 2027, you are not on your own and you still have options. The worst thing to do is nothing. Filing late and paying late are charged separately, the charges build up on fixed dates, and HMRC is generally willing to agree a payment plan if you contact it before things get out of hand.

This guide walks through what each step costs, the dates that matter and how to spread the bill. Our free Self Assessment penalty and payment plan calculator works the figures out for your own dates.

File on time even if you can't pay

The late filing penalty has nothing to do with whether you have paid. Miss the 31 January 2027 online deadline (or 31 October 2026 for paper) and HMRC charges £100, even if you owe nothing. After that it gets worse:

• 3 months late: £10 a day for up to 90 days, so up to £900 more.
• 6 months late: 5% of the tax due or £300, whichever is greater.
• 12 months late: another 5% of the tax due or £300, whichever is greater.

Filing also tells you exactly what you owe. It is the first thing HMRC needs before you can set up a payment plan online, and if you're a CIS subcontractor it may show that you're due a refund. Our 31 January checklist for CIS subcontractors covers the paperwork you need.

What paying late costs

For the 2025/26 bill, two different charges apply to tax you pay late.

Interest. HMRC charges simple interest on everything paid after 31 January 2027 from 1 February 2027 until the day you pay. The rate is the Bank of England base rate plus 4%. It has been 7.75% since 9 January 2026 and changes when the base rate changes. Interest applies to your balancing payment and to your first payment on account for 2026/27, and it keeps running during a payment plan.

Late payment penalties. On top of interest, HMRC adds 5% of the tax still unpaid at 30 days, at 6 months and at 12 months. HMRC's own manual says these penalties apply to the balancing payment, not to payments on account. If you're not sure what that is, read how payments on account work.

Here is what that means for the 2025/26 bill, if your return was filed on time:

So 2 March 2027 is the date that really matters if you can't pay on 31 January. Pay in full by then, or have a payment plan agreed by then, and you only pay interest.

A worked example

Say a self-employed plasterer files online on 20 January 2027 and owes a £2,000 balancing payment plus a £1,000 first payment on account. They can't pay until 15 March 2027.

• Late filing penalty: none, because the return went in on time.
• Interest: £3,000 × 7.75% × 42 days ÷ 365 = about £26.75.
• Late payment penalty: 5% of £2,000 = £100, because 15 March is after 2 March.

Total extra cost: about £126.75. Had they paid by 2 March, or agreed a plan by then, the £100 penalty would not apply.

Setting up a payment plan (Time to Pay)

If you can't pay in full, HMRC can agree a payment plan, often called Time to Pay. You pay what you owe in monthly instalments, plus interest.

Online, without speaking to anyone

HMRC says you can set up a Self Assessment payment plan online for bills up to £30,000, as long as you have filed your return. Its earlier guidance also says the online service is for debts of £32 or more, that you can't have other tax debts, other payment plans or returns outstanding, and that the plan must be set up no later than 60 days after the due date. For the 31 January 2027 bill, that means by about 1 April 2027. Online plans can run for up to 12 months.

By phone

If you owe more than £30,000, need longer than 12 months, or don't meet the other conditions, call HMRC's Self Assessment payment helpline. HMRC says there is no fixed time limit on how long a plan can last. It will ask about your income and spending, and usually expects you to pay about half of what you have left each month after essential costs. Have your UTR, bank details and a rough monthly budget ready.

Does a plan stop the penalties?

A plan agreed before a penalty date, and kept to, means that late payment penalty is not charged. A plan agreed after 2 March 2027 cannot undo the first 5%, though it can still stop the later ones. A plan does not cancel late filing penalties, and interest is still charged. If you are going to miss an instalment, contact HMRC straight away.

Paying through your tax code

If you also have a job or a pension taxed through PAYE, HMRC may collect a small bill through your tax code instead. For the 2025/26 bill you must:

• owe less than £3,000 (you can't make a part payment to get under it);
• already pay tax through PAYE;
• file online by 30 December 2026, or on paper by 31 October 2026.

HMRC then takes the bill in 12 equal amounts from your wages or pension over 2027/28. It won't do this if you don't earn enough through PAYE, if it would take more than half of your PAYE income or mean paying more than twice your usual tax. Voluntary Class 2 National Insurance can't be collected this way.

What to do now

1. File your return as early as you can, so you know the bill. Use our Self Assessment deadlines guide and the HMRC dates calendar.
2. Check for a CIS refund if you're a subcontractor: deductions may cover more of the bill than you think. Try the CIS refund estimator.
3. Pay what you can by 31 January 2027. Less unpaid means less interest.
4. Pay or agree a plan by 2 March 2027 to avoid the first late payment penalty.
5. Plan for next year. Use the tax set-aside calculator to put money away from every job, and the payments on account calculator to see what is due in July.

If HMRC has already written to you, our explainer for late filing penalty letters sets out what the letter means and your deadline to appeal. If you think the penalty is wrong, you normally have 30 days to appeal, for example if you have a reasonable excuse such as serious illness.

Rules and rates are as published on GOV.UK on 2 November 2026. HMRC decides whether a plan is agreed and what you pay, and the interest rate can change. This guide is not tax advice.