Payments on account calculator
A payment on account is an advance on next year's tax, which catches many people out. Put in last year's bill and see whether you owe them and how big each is.
Payments on account calculator
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Two equal halves
Each payment on account is half of last year's bill. They fall on 31 January and 31 July, with the balance for the year due the following 31 January.
When you do not owe them
You generally do not make payments on account if last year's bill was under £1,000, or if more than 80% of your tax was collected outside Self Assessment, such as through your tax code.
The first year is the shock
In your first year of filing you can pay your bill and the first payment on account together on 31 January. Setting money aside through the year is the only way to soften it.
Figures for the 2026/27 tax year, checked 25 October 2026. Sources: Payments on account. An estimate, not advice. SideTill is not tax software.
Keep the number for every month
SideTill is the simple record of your side hustle: log the job, send the invoice, record the money when it comes in, and see whether the month actually made you money. It also shows your best month, so you can tell a bad month from a bad habit.
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Questions
Can I reduce them?
If your income has fallen you can ask HMRC to reduce them. Do not guess: use the figures on your return.
Is this tax advice?
No. It is a rough calculation from the published rule. Use your own return and HMRC for exact amounts.
Where do I find my bill?
On last year's Self Assessment calculation, in your HMRC account or on the return.