About the UK Payments on Account Calculator
If you file a Self Assessment tax return, HMRC usually asks you to pay next year’s tax in advance through two payments on account, each half of last year’s Self Assessment bill, due on 31 January and 31 July. The following January you pay a balancing payment for any tax still owed — on the same day as the first payment on account for the next year. This calculator lays out those dates and amounts for the 2026/27 tax year so the January bill does not come as a shock.
Enter your 2025/26 Self Assessment liability (income tax and Class 4 National Insurance due through the return), the tax already collected at source through PAYE or deductions, any payments on account you already made for 2025/26, and your estimate for 2026/27. The calculator checks HMRC’s two exemptions — a bill under £1,000, or more than 80% of tax collected at source — and works out each payment.
It is designed for the self-employed, landlords, company directors and anyone with untaxed income, especially in their first or second year of self-employment, when the first January bill can include a full year’s tax plus half again. Capital gains tax and student loan repayments are not included in payments on account, so leave them out of the figures.
With the default inputs, the pay by 31 january 2027 is £6,000.00. Change any value above to recalculate instantly.
How to use the uk payments on account calculator
- 1Enter your 2025/26 Self Assessment bill from your tax calculation.
- 2Add the tax already taken through PAYE or other deductions at source.
- 3Enter the payments on account you made towards 2025/26 (0 if first year).
- 4Estimate your 2026/27 Self Assessment bill.
- 5Read what to pay on 31 January 2027, 31 July 2027 and 31 January 2028.
Formula and method
Each payment on account is half of the previous year’s Self Assessment liability (income tax and Class 4 NI due through the return, excluding capital gains tax and student loan repayments). They are not required if that liability was under £1,000, or if more than 80% of your total income tax was deducted at source, for example through PAYE.
In January you pay any balance left for the previous year after its payments on account, plus the first payment on account for the current year; the second payment follows in July. Once the current year’s return is filed, the balancing payment is the actual bill minus the two payments on account, due the next 31 January alongside the first payment for the following year. The 2027/28 payment here assumes the same tax collected at source.
- POA
- Payment on account (due 31 January and 31 July)
- SA bill
- Income tax + Class 4 NI due through Self Assessment
Worked examples
Established sole trader with rising profits
Last year’s £8,000 bill sets each payment on account at £4,000. January 2027 is the £2,000 still owed for 2025/26 plus the first £4,000. If 2026/27 comes in at £10,000, January 2028 brings a £2,000 balancing payment plus £5,000 on account for 2027/28.
First year of self-employment
No payments were made for 2025/26, so January 2027 is the full £6,000 bill plus a £3,000 first payment on account — £9,000 in one go. From then on the payments settle into £3,000 every January and July.
Employee with a small Self Assessment bill
The Self Assessment bill is under £1,000 (and 93% of tax was collected through PAYE), so there are no payments on account. Each year’s £900 is simply paid on the following 31 January.
Frequently asked questions
How are payments on account calculated?+
Each payment on account is half of your previous year’s Self Assessment tax bill, including Class 4 National Insurance but excluding capital gains tax and student loan repayments. They are due by midnight on 31 January and 31 July.
When don’t I have to make payments on account?+
You do not need to make them if last year’s Self Assessment bill was under £1,000, or if more than 80% of all the tax you owed was collected at source, for example through PAYE or deducted from interest.
What is a balancing payment?+
It is the difference between your actual tax bill for the year and the payments on account you made. It is due by 31 January after the tax year ends, on the same day as your first payment on account for the next year.
Can I reduce my payments on account?+
Yes. If you expect your income to fall, you can apply online or use form SA303 to reduce them. If the final bill turns out higher, HMRC charges interest on the shortfall from the original due dates.
Why is my first January tax bill so big?+
In your first year of Self Assessment you pay the whole of the previous year’s tax plus the first payment on account for the current year — up to 150% of a year’s tax — on the same 31 January.
Tax results are estimates based on published rules and simplified assumptions. They are not tax advice — check official guidance or a tax professional for your situation.