Check your Simple Assessment tax bill

You may get a Simple Assessment letter from HM Revenue and Customs (HMRC) if you:

  • owe Income Tax that cannot be automatically taken out of your income
  • owe HMRC £3,000 or more
  • have to pay tax on the State Pension

HMRC will send your Simple Assessment letter either:

This guide is also available in Welsh (Cymraeg).

Understanding your tax bill

Your letter will show:

  • your taxable income (for example, income from pay, pensions or state benefits)
  • any Income Tax you’ve paid
  • the tax you owe

Check the amounts in your letter match those in your records, for example in your P60, bank statements or letters from the Department for Work and Pensions (DWP).

If you get state benefits paid every 4 weeks, work out the total paid in a year by multiplying your regular payment by 13 (not 12).

You may be able to use the HMRC tax checker to estimate how much tax you should have paid in the previous tax year.

If you do not understand your calculation, you can get advice from HMRC or a professional, for example a tax advisor or accountant.

Paying your tax bill

If the amounts are correct, you need to pay your Simple Assessment tax bill.

You must pay by either:

  • 31 January - for any tax you owe from the previous tax year
  • within 3 months of the issue date, if you got your letter after 31 October

The tax year runs from 6 April to 5 April.

If you cannot pay your tax bill in time

HMRC may suggest you pay what you owe in instalments.

If you think your tax calculation is wrong

If you think the amounts used in your calculation are wrong, call or write to HMRC within 60 days.

You’ll need to specify which amounts you think are incorrect and what the amounts should be.

What happens next

If HMRC agrees that your Simple Assessment was wrong, you’ll be sent a new Simple Assessment letter.

If they disagree, you’ll get a decision letter explaining why, how to pay and how to appeal.

You’ll still need to pay your Simple Assessment tax bill by the deadline unless HMRC tells you they’ll delay your payment date.

How to appeal

If you disagree with HMRC’s response, you can make an appeal. Your decision letter will tell you how to do this.

You have 30 days from the date your decision letter was issued to appeal.

Tell HMRC if you have any extra information or if you think they’ve missed something. Include what you think the correct figures are and how you’ve calculated them.

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