HMRC has started sending out P800 Tax Calculations for 2010/11

Published: Thursday 4 August 2011

What you should do if you receive a P800

If you receive a P800 Tax Calculation it means that HMRC’s PAYE records show that you have either overpaid or underpaid tax. HMRC is dealing with people who have overpaid first and will contact those who have underpaid later in the year. 

How do overpayments and underpayments happen in the PAYE system?
Most people will have paid the right amount of tax (and so won’t get a P800 Tax Calculation). For those that haven’t it is usually because their circumstances have changed during the year. Common examples are where a person has:

  • changed jobs;
  • got more than one job;
  • started receiving pension income; or
  • been made redundent.

My P800 shows an overpayment

If you receive a P800 showing that you have overpaid tax, you should check it to make sure the details are right. Assuming they are you should receive your repayment within three weeks. If the details on the P800 aren’t right or you are not sure you should contact HMRC to let them know. 
My P800 shows an underpayment
If you receive a P800 showing that you have underpaid tax, you should check it to make sure the details are right. You should also check that you can afford to pay the tax to HMRC as they suggest (this will usually be through your PAYE tax code in 12 monthly instalments from April 2012). 

You should contact HMRC if:
  • the details on the P800 aren’t right;
  • you are not sure if the details are right;
  • it would cause you financial difficulty to pay the tax back over 12 months; or
  • HMRC had all the information to ensure you paid the correct tax, but failed or delayed to use it.

The calculation may be incorrect, or you may be able to agree a different payment plan or you may not have to pay the tax at all.


If you would like help checking your P800 or help dealing with HMRC call Sarah Price on 01242 237661 or email


HMRC never send details about tax overpayments by email. If you receive an email about your tax position claiming to be from HMRC or you are asked to provide personal or payment information it is probably frudulent. If you receive any suspicious emails please forward them to and do not disclose any personal information.