If your tax underpayment isn’t being collected through Pay As You Earn (PAYE), HMRC will usually issue a Self Assessment tax calculation (SA302).
This shows how much tax they think you owe. It’s a formal bill, and it creates a legally enforceable debt. That means by law, you have to pay it but don’t forget – it may not be correct and there is help if you’re worried about how to afford it.
You might also receive a Statement of Account or an Annual Tax Summary. These give information about your tax position, but they are not formal demands for payment.
First, check the calculation
Before you think about paying, check the figures carefully.
Make sure:
- All your income has been reported correctly
- Any expenses or reliefs you claimed have been included
- The numbers match your tax return
If something doesn’t look right, get advice (there’s information about where to get help further down this page). Don’t assume HMRC are automatically correct.
When do you have to pay the tax?
The SA302 will show:
- The amount of income tax due for that tax year
- The payment deadline
The main deadline is usually 31 January following the end of the tax year.
If your tax return was filed close to that deadline, the payment date may already have passed. If so, HMRC will charge interest on the late payment.
What are payments on account?
If your tax bill for the year is over £1,000, the calculation will usually include payments on account for the next tax year.
These are advance payments towards next year’s bill.
- The first is due on 31 January
- The second is due on 31 July
Interest is charged if these aren’t paid on time.
Find out more about payments on account.
Can you reduce payments on account?
Yes – but only in the right circumstances.
If you expect your income to be lower in the next tax year, you can ask HMRC to reduce your payments on account. This can be done online or by submitting form SA303.
It’s important to know if you reduce your payments on account, you will still be charged interest. If you reduce them too much, you could face another bill later.
If you’re worried about paying.
A formal tax bill can feel overwhelming. But ignoring it usually makes things worse.
If you can’t pay in full, you may be able to arrange an affordable payment plan. The sooner you speak to HMRC, the more options you’re likely to have.
If you’re on a low income and can’t afford professional tax advice, we can help you understand your bill and work out what to do next. Find out more about the help we can give you.