Payments on account calculator

What payments on account are

Payments on account are advance payments towards your next Self Assessment bill. Each one is normally half of your latest bill, due on 31 January and 31 July. The first one lands on the same day as the balancing payment for the tax year just ended, which is why the January bill can feel double. This page follows GOV.UK’s payments on account guidance, checked in October 2026.

The worked example

So the January 2027 total is £6,000, not £4,000. Use the calculator above with your own figures.

When you do not have to make them

GOV.UK says you must make payments on account unless either of these applies:

• the Self Assessment tax you owed for last year was less than £1,000, or
• you paid more than 80% of your tax outside Self Assessment, for example through your tax code (PAYE) or tax taken from savings interest.

The calculator applies exactly these two tests to the figures you enter.

What the calculator does not cover

• Reducing your payments. If you expect a lower bill this year you can ask HMRC to reduce them, but if you reduce them too far HMRC charges interest on the shortfall from the original due dates. Read GOV.UK first.
• Capital Gains Tax and student loans. Payments on account are based on Income Tax and Class 4 National Insurance; check on GOV.UK how other amounts on your bill are treated.
• Your real figures. Use the amounts on your HMRC online account or your Self Assessment calculation, not an estimate, before you pay.
• Interest and penalties if you pay late. See our 31 January 2027 guide.

Getting the money together

If the January figure is a shock, tell HMRC before the deadline: you may be able to set up a payment plan online. Allow a few days for the payment to reach HMRC. If you are in Making Tax Digital, check when it applies to you.

Altto is not affiliated with HMRC. This is general information, not tax advice.

Altto is not affiliated with HMRC. This is general information, not tax advice.