Written and reviewed by James Whitfield · Updated August 2026 · Checked against 2026/27 HMRC rates · Editorial standards · Methodology
Payments on account are advance payments toward the following year's tax bill. They catch many new sole traders off guard. This guide explains how they are calculated, when they are due and when you can reduce them.
Payments on account are advance payments toward next year's Self Assessment bill. They kick in if your bill tops £1,000 and less than 80% of your tax was collected through PAYE.1 You make two: one on 31 January and one on 31 July, each equal to 50% of the previous year's Income Tax and Class 4 NI. The sting is the first year they apply — your 31 January payment covers the whole year you have just finished plus the first instalment toward the next one, so it can feel like about 150% of a single year's tax landing at once. If your income is falling, you can ask HMRC to reduce them using form SA303.
If your Self Assessment tax bill exceeds £1,000 and less than 80% of it was collected through PAYE, HMRC requires you to make advance payments toward the following year's bill. These are called payments on account.
There are two payments each year: the first is due on 31 January (the same date as the prior year's balancing payment), and the second is due on 31 July. Each payment is equal to 50% of the prior year's total Self Assessment tax and Class 4 NI bill. Class 2 NI and student loan repayments are excluded from the calculation.
The logic is that HMRC assumes your income will be similar next year. By collecting half upfront in January and half in July, you are funding the following year's tax as you go rather than paying a large lump sum 20 months after the income was earned.
The payments on account system is most painful in the first year you file a Self Assessment return. In January after your first trading year, you pay both your year 1 tax bill and the first payment on account for year 2 simultaneously.
Take a sole trader whose first year earns £40,000 of taxable profit. Their Income Tax and Class 4 NI bill is £7,132 (the exact figure the calculator on this site produces). Here is what actually leaves their account:
| 31 Jan 2028 — year 1 balancing payment | £7,131.80 |
| 31 Jan 2028 — first payment on account (50%) | £3,565.90 |
| Total due 31 January 2028 | £10,697.70 |
| 31 Jul 2028 — second payment on account (50%) | £3,565.90 |
| Paid toward tax by 31 July 2028 | £14,263.60 |
This is a common reason new sole traders are caught short. Many assume they have until January to pay only the first year's tax, not realising they simultaneously owe 50% of the estimated second year bill on the same day. The £3,566 you pay in July then counts toward year 2, so you are not paying twice — but you do need the cash on the two dates. Putting money aside monthly throughout the year is what turns this from a crisis into a formality.
If you expect your income to be lower in the following year — because you have a slow period, changed working hours, or have taken on significant new expenses — you can apply to reduce your payments on account. This is done online through your HMRC Self Assessment account or by submitting form SA303.
Reducing your payments on account is a reasonable approach if your income has genuinely fallen. However, if you underestimate and your actual bill turns out higher than the reduced payments, HMRC charges interest from the original due date on the underpaid amount. The interest rate is currently around 7.75%.
If you overpay through payments on account — because your income was lower than the prior year — HMRC refunds the excess once you file your return. The refund can be offset against any other tax owed or paid directly to your bank account.
You stop paying payments on account in any year where your bill is expected to be below £1,000 or where more than 80% of your tax is being collected through PAYE. If your sole trader income falls significantly or you return to employment, your payments on account should be nil.
You must still file a Self Assessment return even if you expect no tax due, until you formally deregister from Self Assessment. HMRC will not automatically stop expecting payments on account — you need to either file a return showing a nil bill or request to reduce them.
Advance payments toward the following year's tax bill, each equal to 50% of the prior year's bill. Due on 31 January and 31 July each year.
Yes, if you expect your income to be lower. Apply online through your HMRC account or using form SA303. Be accurate — underestimating incurs interest on the shortfall.
You do not pay them during the first year, but on 31 January after your first year you pay both the year 1 bill and the first payment on account for year 2 simultaneously.
50% of the prior year's total Self Assessment tax and Class 4 NI bill (excluding Class 2 NI and student loan repayments). So a prior year bill of £8,000 means two payments of £4,000 each.
The rates, thresholds and rules in this article are drawn from the official HMRC and GOV.UK sources below, using the confirmed 2026/27 figures. Each link opens the relevant official page in a new tab.