HOW IT WORKS

Two advance payments towards next year’s tax.

Payments on account for 2026/27 are generally due when your Self Assessment amount after tax collected at source is £1,000 or more, and less than 80% of your total liability was collected at source. Each payment is 50% of that Self Assessment amount: one is due on 31 January and the other on 31 July.

If you expect next year’s income to fall, you can ask HMRC to reduce your payments. If you reduce them too far, HMRC may charge interest on the underpaid amount.

01 / THE CALCULATOR

Plan for both deadlines.

Enter your 2025/26 Income Tax and Class 4 NI liability, tax deducted at source and any payments on account already paid for 2025/26.

Your tax figures

2025 / 26
Income Tax + Class 4 NI; exclude student loan and Capital Gains Tax
£
Optional · for example, PAYE tax from employment
£
January and July 2026 payments · leave at £0 in your first year
£

Your Self Assessment amount is the total liability less tax already deducted at source. Payments already made for 2025/26 reduce the balancing payment, but not the 2026/27 instalments. Check your Self Assessment statement for the actual amount due.

DO PAYMENTS ON ACCOUNT APPLY?
Yes — two instalments
Each instalment: £1,500.00
Estimated amounts due2027
Total Income Tax + Class 4 NI liability · 2025/26£3,000.00
Tax already deducted at source£0.00
Self Assessment amount£3,000.00
Payments on account already paid · 2025/26£0.00
Balancing payment due · 31 January 2027£3,000.00
First payment on account · 2026/27£1,500.00
Total due · 31 January 2027£4,500.00
Second payment on account · 31 July 2027£1,500.00
MONTHLY SET-ASIDE FOR 31 JANUARY£900.00 / month£4,500.00 total due ÷ 5 months remaining.

If you ask HMRC to reduce payments on account, make sure the new estimate is realistic. Interest may apply if the reduced payments are too low.

WORKED EXAMPLE

A £3,000 bill, with no tax paid at source.

Assuming no tax was deducted at source and no payments on account were already paid for 2025/26, the balancing payment is £3,000. Each 2026/27 payment on account is £1,500, so the January total is £4,500 and the July payment is £1,500.

31 January 2027£4,500.00
31 July 2027£1,500.00
IF YOU EXPECT LOWER PROFITS

Reducing payments on account

If you expect your 2026/27 tax bill to be lower, you can ask HMRC to reduce your payments on account using form SA303 or the online service in your HMRC account. HMRC may charge interest if the reduced payments are less than the amount due.

02 / NEXT STEPS

Keep the rest of your tax year organised.

Estimate your tax bill, then keep income, expenses and mileage together through the year.

Use the main tax calculator Get the Self Assessment Spreadsheet on Etsy ↗Visit the Etsy shop ↗
Tax calculatorMileage calculatorSelf Assessment checklistFor accountants

This is a general estimate for the 2025/26 tax year, not tax advice or an HMRC calculation. Your Self Assessment statement and personal circumstances determine the amounts you actually owe.