What is a P800 form?

A P800 tax calculation is a form used by HMRC to inform individuals when they have paid an incorrect amount of tax.

The P800 is calculated and sent by HMRC whenever there is an overpayment (meaning you are due a tax rebate) or underpayment of income tax.

HMRC doesn’t have a specific time for sending out a P800. Instead they can send it at any point during the tax year when their system detects an overpayment or underpayment.

The P800 shows your:

  • total income.
  • total tax paid.
  • tax free personal allowance.
  • tax deductible expenses incurred in that tax year.

It’s important to understand how your P800 tax calculation works to ensure the information stated on the form is correct for your particular situation.

Why have I been sent a P800 tax calculation?

If you receive a P800 from HMRC there are typically two possible reasons for it:

  • HMRC believes that you have overpaid income tax and are entitled to a P800 tax rebate.

Common reasons for receiving a P800 for paying too much tax include changing jobs, claiming back work related expenses and taking a pension lump sum.

  • HMRC has calculated that you have not paid enough tax and you have a tax bill to pay.

Common reasons for being sent a P800 for underpaying tax include having an incorrect tax code, having more than one form of PAYE employment at the same time and receiving allowances that you weren’t entitled to.

How do I work out a P800 form?

HMRC will generally send you a P800 tax calculation for each tax year in which you have either paid too much or too little tax.

There are a variety of tax forms which can be used to check your tax position with the most popular under the PAYE system being a P60 and P45.

P800 tax calculation explained

In this example, we’ll assume that a tax rebate is owed by HMRC.

The figure in THE RESULT box on each year’s P800 tax calculation are NOT to be added together – as they accumulate each year. So the total figure you are owed will be shown on the last tax calculation form.

For example, if you are owed a tax rebate for two years, say the 2013-2014 and 2014-2015 tax years, the total amount of tax rebate you are due will be the figure presented in THE RESULT box on the 2014-2015 tax calculation form.

Generally you won’t receive a separate refund payment for each tax year with HMRC combining what you are owed before paying you.

Check your P800 tax calculation

P800’s aren’t always correct, so it is always best to check your form to ensure you are not paying too much or too little tax.

The tax office will ask you to check your P800 to make sure that all the information included is correct. If it’s wrong you can overpay or underpay income tax.

How to claim a P800 tax refund

If the P800 indicates that you are owed a tax refund you may be able to claim it online through the HMRC website: www.gov.uk/p800refund.

This is typically the quickest way to receive your money, with a turnaround time of less than a week. If you fail to make an online claim within 45 days HMRC will send you a cheque through the post instead.

In the event that you do not have the option to claim online HMRC will send you a cheque automatically. You do not need to take any action, as the cheque should arrive within two weeks from the date on your P800.

If your tax refund covers multiple years, HMRC will normally combine all amounts owed into a single payment.

P800 tax refunds

It’s important to note that you will only receive a P800 tax refund if HMRC is already aware of the money owed to you.

If you are owed a tax rebate under PAYE due to expenses incurred at work you will not automatically receive a refund meaning you have to request your entitlement from HMRC by making a claim.

The process for filing a tax rebate claim differs based on the specific expenses you are claiming.

Our tax guides are designed to assist you in understanding what expenses you may qualify for and how to properly submit your claim to HMRC.

P800 underpayment of tax

If you get a P800 showing that you have underpaid tax up to £2999.99 HMRC will normally collect what you owe through your tax code.

HMRC typically recovers any outstanding tax by adjusting your PAYE tax code for the upcoming tax year, as long as your income surpasses the personal allowance and covers the unpaid amount.

You can expect to receive a coding notice prior to the 5th of April, which will indicate the reduced code.

HMRC simple assessment

HMRC can issue a simple assessment (form PA302) when they suspect that you have underpaid income tax from your PAYE earnings.

Typically a simple assessment is not used when HMRC needs to reconcile your income tax for multiple tax years.

The primary factors for a simple assessment  by HMRC for issuing a PA302 are as follows:

  • You owe income tax that cannot be deducted directly from your current earnings.
  • You owe HMRC £3,000 or more in tax.
  • You owe HMRC tax on state pension income.

Have questions about your P800?

If you have received a P800 and have a question and you don’t have an accountant you should call HMRC (the tax office).

You can call HMRC on 0300 200 3300 or get in touch online through the digital assistant after you have accessed your personal tax account or HMRC app.

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