Payments on Account Calculator

Updated for 2026/27 · No signup · Estimate only, not financial advice

If your last Self Assessment tax bill was over £1,000 (and less than 80% was collected via PAYE), HMRC usually requires two Payments on Account of 50% each towards next year's bill — due 31 January and 31 July.

Worked example

If your Self Assessment bill for the year was £6,000, you'd typically owe that £6,000 plus a first Payment on Account of £3,000 (50%) by 31 January, then a second Payment on Account of £3,000 by 31 July — a total of £9,000 due in January.

Common mistakes

Forgetting Payments on Account exist and being caught out by a much larger January bill than expected.
Not applying to reduce Payments on Account when income has genuinely dropped — you can ask HMRC to reduce them if you expect to earn less.
Missing the 31 July second instalment, which accrues interest just like the January payment.

How Payments on Account are actually calculated

HMRC calculates each Payment on Account as exactly 50% of your previous year's total Self Assessment tax bill — not an estimate of what you'll owe this year, but a fixed figure based on history. Two instalments are due: the first on 31 January (paid alongside your balancing payment for the year just ended), and the second on 31 July.

Worked example: if your 2025/26 Self Assessment bill came to £5,000, HMRC would set two Payments on Account of £2,500 each towards 2026/27 — one due 31 January 2027 (on top of any balancing payment for 2025/26 itself), and the second due 31 July 2027. If your actual 2026/27 bill turns out to be £6,000, you'd pay the £1,000 shortfall as a balancing payment the following January; if it's lower, you'd get a refund or credit.

You only make Payments on Account if your previous year's bill was over £1,000 and less than 80% of your tax was already collected at source (for example through PAYE) — so most people who are mostly employed with a small side income won't be affected, while sole traders and landlords with substantial untaxed income usually are.

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Sole Trader Tax Calculator Self Assessment Deadlines Self-Employed Hub

FAQ

Who has to pay Payments on Account?

Anyone whose Self Assessment tax bill was over £1,000, unless more than 80% of their tax was already collected at source (for example through PAYE).

When are Payments on Account due?

The first instalment is due 31 January (alongside your balancing payment), and the second is due 31 July, each equal to 50% of your previous year's tax bill.

Can I reduce my Payments on Account?

Yes — if you genuinely expect to earn less this year, you can apply to HMRC to reduce your Payments on Account. Reducing them too far when you shouldn't can trigger interest charges later.