Self Assessment payments on account: what they are and when they are due

Payments on account are two advance instalments towards your next Self Assessment bill, due on 31 January and 31 July. This guide explains how they are worked out, who does not pay them, how to ask for a reduction and what late payment costs, using GOV.UK pages checked on 14 October 2026.

What payments on account are

Self Assessment is the system HMRC uses to collect Income Tax from people whose tax is not fully taken through a job or pension, such as the self-employed, landlords and people with significant other income. HMRC usually asks for part of the next bill in advance. These advance instalments are called payments on account. They count towards Income Tax and, for the self-employed, Class 4 National Insurance, which is the contribution charged on profits.

The idea is simple. HMRC bases the two instalments on your estimated earnings, usually last year's. Each instalment is normally half of last year's tax bill. If this year's tax then turns out higher than the two instalments added together, you pay the difference as a balancing payment. If it turns out lower, you may be able to claim a refund of the overpayment.

The dates and the key figures

For the 2026/27 tax year, which runs from 6 April 2026 to 5 April 2027, the pattern works like this. The balancing payment for 2025/26 and the first payment on account for 2026/27 are both due on 31 January 2027, so two amounts fall due on the same day. The second payment on account for 2026/27 is due on 31 July 2027. Any balancing payment for 2026/27 itself is then due on 31 January 2028. The January payment can therefore be much larger than people expect.

Who has to pay them, and who does not

GOV.UK says you must make both payments unless one of two things applies. The first is that your Self Assessment bill for the previous year was less than £1,000. The second is that more than 80% of last year's tax was already paid some other way, such as through your tax code or through tax taken off savings interest by a bank. In either case, the whole bill is simply due on 31 January after the tax year ends.

This guide applies to people who file a Self Assessment return and have a bill above those limits. It does not apply to people whose tax is fully handled through PAYE (Pay As You Earn, the system where an employer or pension provider deducts tax) and who do not file a return. Income Tax rates and bands differ in Scotland, which can change the size of a bill, but GOV.UK sets out one set of payment on account rules and dates.

A worked example

The following figures are illustrative only and are not a forecast of any real bill. For example, suppose someone's 2025/26 Self Assessment bill is £4,000, and during that year they made two payments on account of £1,800 each, a total of £3,600. The balancing payment is £4,000 minus £3,600, which is £400. The first payment on account for 2026/27 is half of £4,000, which is £2,000. On 31 January 2027 the total due is therefore £400 plus £2,000, which is £2,400. On 31 July 2027 a second payment of £2,000 is due. Across the two dates that is £2,400 plus £2,000, or £4,400.

If your income falls: reducing the payments

Because the instalments are based on last year, they can be too high if income has dropped. GOV.UK says you can ask HMRC to reduce your payments on account, either online by choosing "Reduce payments on account" after viewing your latest return, or by posting form SA303. You need to state the amount you expect to owe. The form page lists the usual reasons: profits or other income have gone down, the tax relief you are entitled to has increased, or more tax was taken at source than in the previous year. The claim must be made by 31 January after the end of the tax year.

The risk runs the other way if the reduction is too large. GOV.UK says that if you reduce your payments and your bill ends up higher than expected, you will be charged interest on the difference. As an illustration only, if the shortfall were £1,000 and the rate of 7.75% applied for a full year, simple interest would be £1,000 multiplied by 0.0775, which is £77.50. The real figure depends on the dates and on rates at the time, which can change.

Paying, paying late and getting help

GOV.UK lists several ways to pay, including online bank account payments, online or telephone banking, CHAPS, debit card, Bacs, Direct Debit and cheque by post, and says weekly or monthly instalments are available before the deadline. Processing times vary from the same or next day for Faster Payments and cards to about 5 working days for a new Direct Debit, so it can be worth allowing time. Payments cannot now be made at the Post Office.

Paying late brings interest, and may bring penalties. On the penalties page, GOV.UK shows late payment penalties of 5% of the unpaid tax at 30 days, at 6 months and at 12 months. Interest on tax paid late was 7.75% on the HMRC rates page as of 14 October 2026, with 2.75% paid on overpaid tax that is refunded. If paying in full is not possible, GOV.UK says HMRC may agree a payment plan after checking affordability. Free, impartial help is available from Citizens Advice, MoneyHelper and StepChange.

Check before you act

Rules, rates and interest can change, and every tax position is different. It can be worth confirming the details on the official GOV.UK pages linked below, and in your own HMRC online account, before relying on any figure in this guide.

Sources

• GOV.UK, Understand your Self Assessment tax bill: payments on account
• GOV.UK, Understand your Self Assessment statement: balancing payments
• GOV.UK, Pay your Self Assessment tax bill
• GOV.UK, Claim to reduce your payments on account (SA303)
• GOV.UK, Self Assessment penalties
• GOV.UK, HMRC interest rates for late and early payments
• GOV.UK, Difficulties paying HMRC