31 July is the Self Assessment deadline for your second payment on account: an advance payment towards the current year's tax bill, equal to 50% of the previous year's Self Assessment liability. It is a payment deadline only. No return is due. The 31 July 2026 deadline has passed. The next one is 31 July 2027, the second payment on account towards your 2026/27 tax, and it falls on a Saturday. You do not need to make payments on account if last year's Self Assessment bill was under £1,000, or if more than 80% of your tax was collected at source. Late payments attract interest, currently 7.75% a year.
What is due on 31 July?
Self Assessment has two payment dates each year:
- 31 January. The balancing payment for the tax year that ended the previous April, plus the first payment on account for the current year;
- 31 July. The second payment on account for the current year.
Each payment on account is half of the previous year's "relevant amount": your income tax and Class 4 National Insurance under Self Assessment, after tax already deducted at source. Capital gains tax and student loan repayments are not included. They go into the balancing payment the following January.
Worked illustration (not an HMRC figure): your 2025/26 Self Assessment bill, after PAYE, is £8,000. You pay that £8,000 by 31 January 2027, together with a first payment on account of £4,000 for 2026/27. A second £4,000 is due by 31 July 2027. If your final 2026/27 bill turns out to be £10,000, the remaining £2,000 is due on 31 January 2028, along with the first payment on account for 2027/28.
Who has to pay on 31 July?
You must make payments on account unless either of these applies:
- Small bill. Your Self Assessment liability for the previous year, after tax deducted at source, was less than £1,000;
- Mostly taxed at source. More than 80% of your previous year's income tax was collected at source, for example through your PAYE tax code.
Employees with one untaxed side income usually fall outside the regime. The self-employed, landlords and people with large untaxed investment income usually fall within it. Payments on account often come as a surprise in the first year of self-employment, when the January bill covers the whole first year plus half of the next. Our main guide to payments on account covers how the cycle works.
Paying on time: the weekend point for 31 July 2027
When a deadline falls on a weekend or bank holiday, HMRC says your payment must reach it on the last working day before. That is Friday 30 July 2027. This does not apply if you pay by Faster Payments or by debit or credit card, which usually arrive the same or next day. Other timings:
- Faster Payments, CHAPS or card. Same day or next day;
- Bacs. Usually 3 working days;
- Direct Debit. 3 working days with an existing Direct Debit, 5 working days if it is your first Direct Debit with HMRC;
- Budget Payment Plan. You can pay weekly or monthly in advance of the deadline, which spreads the cost.
The payment reference is 11 characters: your 10-digit UTR followed by the letter K. A wrong reference can delay the payment or put it against a different bill.
What happens if you miss the 31 July deadline
Interest, not a penalty. The automatic 5% late payment penalties in Schedule 56 to the Finance Act 2009 apply to the balancing payment, not to payments on account. A late second payment on account therefore carries late payment interest from the day after it was due until it is paid. The rate is the Bank of England base rate plus 4%: 7.75% from 9 January 2026, with the base rate at 3.75%. Our guide to HMRC interest rates tracks any changes.
Other penalties may be running by July. If the previous year's balancing payment, due on 31 January, is still unpaid, late payment penalties of 5% of the unpaid tax are charged at 30 days, 6 months and 12 months. If the return itself has not been filed, the late filing penalties also increase: after 6 months, the greater of 5% of the tax due or £300 is added to the £100 initial penalty and up to £900 of daily penalties.
If you cannot pay, contact HMRC before the deadline. You may be able to set up a payment plan to pay in instalments. Interest is still charged on the unpaid tax.
Reducing your 31 July payment
If you expect your income to fall, for example because a contract ended, you stopped letting a property or profits dropped, you can ask HMRC to reduce your payments on account. You can do this online through your Self Assessment account or by sending form SA303 (see HMRC's payments on account guidance). You must state the amount you expect to owe.
Be careful. If you reduce too far and the final bill is higher, HMRC charges interest on the difference. Section 59A(6) of the Taxes Management Act 1970 also allows a penalty, up to the shortfall, where a reduction claim was made fraudulently or negligently. Base the claim on real figures, not hope.
If your income is rising, payments on account based on last year's figures will be too low. Setting money aside for the January balancing payment avoids a cash-flow shock. Some taxpayers also have to keep digital records and send quarterly updates under Making Tax Digital from April 2026, which gives an earlier view of the likely bill.
Key Self Assessment dates for 2026/27
- 31 October 2026. Paper returns for 2025/26;
- 30 December 2026. Online filing deadline if you want an underpayment collected through your tax code;
- 31 January 2027. Online returns for 2025/26, the 2025/26 balancing payment and the first payment on account for 2026/27;
- 31 July 2027. The second payment on account for 2026/27 (pay by 30 July unless you use Faster Payments or a card).
Acumon's self assessment team prepares returns, works out payments on account and handles SA303 reduction claims. Our income tax return service can tell you before January whether reducing your 31 July payment is justified.