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Payments on Account Calculator

See exactly what’s due on 31 January and 31 July, why, and whether CIS or PAYE means you don’t have to pay in advance at all.

Both tests built inThe £1,000 rule and the 80% rule, as HMRC applies them.
January in fullBalancing payment plus first payment on account.
Reduce checkSee if your income drop means you can pay less.
Example figures — replace with your own. Example figures are filled in so you can see how it works — replace them with your own before relying on the result shown.

1. Last year’s tax return

Use the figures from your most recent return (or your best estimate).

Before taking off CIS or PAYE. Leave out student loan, Class 2 and Capital Gains Tax.
Enter 0 or more.
Enter 0 or more.
From a job or pension, if any.
Enter 0 or more.
Paid in January but never part of payments on account.
Enter 0 or more.
0 if this is your first year.
Enter 0 or more.

2. Could you reduce them? (optional)

If you expect to earn less, or have more CIS taken, in 2026/27, enter your best guess of that year’s bill after deductions.

Leave blank to skip. Compared with 2025/26 payments.
Enter 0 or more.

Show the maths

How we got your figure

Each payment on account is half of last year’s bill after tax already deducted at source.

The step-by-step working will appear here.

Guide

How payments on account work

Payments on account are advance payments towards your next tax bill. HMRC assumes this year’s bill will be about the same as last year’s, so it asks you to pay half of it by 31 January and half by 31 July. When you file the return for that year, any difference is settled with a balancing payment (or a refund) the next January.

GOV.UK’s own example

Your bill is £3,000 and you already made payments on account of £1,800. You pay a £1,200 balancing payment plus a first payment on account of £1,500 for the next year — £2,700 by 31 January — and another £1,500 by 31 July. If this was your first year, January would be the full £3,000 plus £1,500: £4,500.

You don’t have to make payments on account if last year’s bill (after tax taken off at source, such as CIS and PAYE) was under £1,000, or if more than 80% of the tax was already deducted at source. That’s why many CIS subbies never pay them. Read more in our payments on account guide.

Things people forget

The first JanuaryYour first bill comes with half of it again in advance — often 1.5× what people expect.
CIS this year doesn’t count yetCIS taken during the current year is only credited when you file that year’s return, not against July’s payment.
Student loan and Class 2They’re paid in January but never included in payments on account.
You can reduce themIf you know this year will be lower, reduce online or with form SA303. Too low, though, and HMRC charges interest.
Interest on late paymentsLate payment interest is the Bank of England base rate plus 4%, charged from the day after the deadline.
RoundingHMRC splits the amount in half and puts any odd penny on the July payment.

Frequently asked questions

What is a payment on account?

An advance payment towards your next Self Assessment bill. Each one is normally half of your previous year’s Income Tax and Class 4 National Insurance, after tax deducted at source. They are due on 31 January and 31 July.

Do I have to make payments on account?

Not if your last Self Assessment bill was under £1,000, or if more than 80% of the tax you owed was already deducted at source, for example through CIS or PAYE.

Why is my first January tax bill so high?

Because you pay the whole bill for the year just finished plus the first payment on account for the current year at the same time. If you owe £3,000 with no payments made before, January would be £4,500.

Does CIS count towards payments on account?

CIS deducted in the previous year counts as tax deducted at source, which lowers the amount payments on account are based on and can mean none are due. CIS deducted in the current year cannot be set against payments on account as you go; it is credited when you file that year’s return.

Can I reduce my payments on account?

Yes, if you expect your bill to be lower, for example because your income has fallen or more CIS is being deducted. You can reduce them in your HMRC online account or with form SA303. If you reduce them too far, HMRC charges interest on the difference.

Are student loan repayments included in payments on account?

No. Student loan repayments, Class 2 National Insurance and Capital Gains Tax are paid with your balancing payment but are never part of payments on account.

CalculatorTax Set-Aside CalculatorHow much to put aside from each invoice, week or month for Income Tax and Class 4 NI, after any CIS.CalculatorCIS Tax & Refund CalculatorCheck the CIS that should have been taken, spot deductions on materials, and estimate your refund or bill.GuidePayments on account explainedWhy January can be 1.5 times your bill, the £1,000 and 80% rules, and how CIS affects them.GuideSelf Assessment deadlines and penaltiesEvery key date for 2025/26 and 2026/27, and exactly what it costs to file or pay late.GuideHow to claim a CIS refundStep-by-step for sole traders, with a worked example and the deadlines for 2025/26.

Sources and review

Last reviewed: 21 October 2026. The rates and rules on this page were checked against GOV.UK guidance on that date by the HandySums team. We re-check every April, after each Budget and whenever GOV.UK changes. HandySums is independent and not an accountancy firm — see how we check our sums.

Estimate only — not tax advice. This calculator applies the payments on account rules published on GOV.UK to the figures you enter. It does not recalculate your tax, and it assumes the figures you enter match your Self Assessment calculation. HMRC’s figures on your statement take priority. Your actual bill depends on your full Self Assessment. Verify with HMRC or a qualified accountant. The figures you enter stay in your browser and are not stored.