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Balancing payment + payments on account

Self Assessment Payment Calculator UK

Estimate what a 31 January payment could contain after your tax return: the remaining balance for the year just ended plus, where HMRC's rules apply, the first payment on account for the following year.

Enter the figures from your tax calculation
The labels deliberately separate your actual bill from the amount used to calculate future payments on account.

Use the final amount due for the tax year before subtracting payments on account already made toward that year.

Include payments on account already paid toward this tax year and any other credits that HMRC has actually allocated to the bill.

Use the relevant Income Tax + Class 4 NI amount after tax deducted at source. Exclude CGT, Self Assessment student/postgraduate loan repayments and Class 2 NI.

For example, through PAYE or other tax deducted at source. When this exception applies, payments on account are not normally required.

Your HMRC statement is the authoritative payment record. This tool is for planning and does not submit, amend or reduce payments on account.
Your January and July estimate will appear here
The result shows whether the £1,000/80% exceptions appear to switch payments on account off.

Example: a £6,000 current bill, £2,500 already paid and a £6,000 relevant amount produces a £3,500 balancing payment plus a £3,000 first payment on account on 31 January.

31 January
Normally pay the balancing amount for the return just filed. If payments on account apply, the first advance instalment is due at the same time.
31 July
The second payment on account is normally due by 31 July and is usually the same amount as the first instalment.
Following 31 January
The next return compares the final bill with payments on account already made, producing either a balancing amount or an overpayment position.
Worked example

A freelancer's completed return shows a total bill of £6,000. They already paid £2,500 toward that year. The relevant amount for the next payments on account is £6,000 and the 80% exception does not apply.

Balancing payment£3,500
First payment on account£3,000
31 January total£6,500
31 July£3,000

This is why a first year with payments on account can create a much larger January cash requirement than the balancing payment alone.

What this tool does not assume

It does not assume that the full Self Assessment bill is automatically the relevant amount for payments on account.

Capital Gains Tax and Self Assessment student/postgraduate loan repayments are not included in the payment-on-account basis, even though they can form part of the balancing payment.

It also does not model a formal claim to reduce payments on account. Use HMRC's process if your expected liability is genuinely lower.

How Self Assessment payments work

Follow the full payment cycle from filing through balancing payments and credits.

Read resource

Payments on account explained

A sole-trader-focused explanation of when advance payments start and how to budget.

Read resource

Cannot pay your Self Assessment bill?

Practical preparation before contacting HMRC about payment difficulties.

Read resource

Official sources

GOV.UK — Payments on accountGOV.UK — Self Assessment tax billHMRC manual — payments on account calculation

How this guidance is reviewed

Author

Written and maintained by UK Tax Toolbox, led by founder Conor Dwyer. Calculator assumptions are checked against the public sources linked on the page.

Last reviewed

12 August 2026

Basis of guidance

Public HMRC and GOV.UK guidance, published tax thresholds and the calculator assumptions stated on each page.

Useful official references

GOV.UK — Payments on accountGOV.UK — Self Assessment tax billHMRC manual — payments on account calculation

Spot something that looks out of date? Use the contact page to flag corrections. Important tax decisions should still be checked with HMRC or a qualified adviser.

Frequently asked questions