P800 tax calculation letters

Information about P800 tax calculation letters that HMRC can send to employees.

HMRC sends P800 letters to your employees when they’ve paid too much or too little tax. These letters are based on the PAYE data you submit. By keeping your payroll records accurate and up to date, you help reduce the risk of errors that lead to these letters.

 NOTE: Week 53 often generates a P800 notice as employees receive 53 weeks of tax free allowance, instead of 52 weeks. 

For more information view how tax and national insurance calculate at week 53.

What is a P800 letter?

A P800 is a tax calculation from HMRC. It tells your employee if they’ve overpaid or underpaid income tax. This happens when the tax collected through PAYE doesn’t match HMRC’s final calculation. The letter explains the difference and what action the employee needs to take.

When are P800 letters sent?

HMRC usually sends P800 letters after they review their PAYE records after the end of a tax year. Employees can start receiving letters between June and March of the following year. 

Your role in preventing errors

You’re responsible for submitting payroll data through Real Time Information (RTI). This includes earnings, tax deductions, and applying the correct tax codes. If the data is late or incorrect, it can lead to tax miscalculations. Using the tax codes HMRC provides, and reporting changes promptly helps avoid this.

How to support employees

If an employee receives a P800, they might come to you with questions. While the letter is between them and HMRC, you can help by directing them to their Personal Tax Account on GOV.UK. They can also use the HMRC app to check their tax code and income. Provide payslips or summaries to help them understand what’s been reported.

When a refund is due

If the P800 shows a refund, HMRC explains how the employee can claim it. Most employees can make online claims using the reference number in the letter.

When tax is owed

If the employee has underpaid tax, HMRC usually adjusts their tax code for the next year. This spreads the repayment across future pay periods. Sometimes, HMRC can ask the employee to pay the amount directly.

To find out more about form P800, go to HMRC's employee guidance at GOV.UK.

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