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The P800 form: what to do if HMRC sent you one

  • 2 min read
  • Last updated 29 Dec 2022

A P800 form, also known as a tax calculation, is a letter that HMRC will send you at the end of the tax year if they think that you have not paid the right amount of tax. 

If you’ve received a p800, then you’ve either paid one of the two:

  • Too much tax
  • Too little tax

What if I think that my P800 form is wrong?

It can happen! P800s aren’t always correct.

But luckily, there are options. You’ll have to:

  1. Compare it with your P60, P45, and P11D forms
  2. Check that HMRC included your flat rate job expenses (uniform laundry allowance, etc.)
  3. Check that HMRC also included your regular job expenses (mileage allowances, professional subscription fees, parking fees, business phone call, travel and overnight costs, etc.)
  4. Also check for adjustments like the married couples’ allowance, etc.

After double (or triple) checking, you may find:

  • Your P800 is correct – you don’t need to do anything
  • You overpaid tax – HMRC will refund you within 4 weeks
  • You underpaid tax but it’s less than £3,000 – HMRC will collect the tax directly through your tax code
  • You underpaid tax and it’s more than £3,000 – HMRC will contact you about a special repayment schedule

It says I can get a tax refund. How do I get it?


To claim an online tax rebate, you’ll need to: 

  1. Go to the HMRC website
  2. Sign in to your Personal Tax Account using your Government Gateway User ID
  3. Follow the steps to request a refund

Once you finish, you should receive the rebate to your bank account in approximately 5 working days.

By phone

You can also call HMRC on 0300 200 3300 where an advisor will process your tax refund.

Wait for a cheque

If you don’t do anything, HMRC will automatically send you a cheque through the post within 14-45 days from the date on your P800.

What if my P800 says I owe tax?

HMRC will either collect the tax you owe through your PAYE tax code or ask you to pay directly.

This will depend on factors such as whether you’re self-employed or employed and how much tax you owe.

What if I have P800s from multiple years?

Each form includes the previous years, so you only need the one from the final year.

I didn’t get one. Can I still claim a tax refund?

The short answer is yes.

You could still be owed tax from any expenses or tax reliefs that HMRC doesn’t know about.

For example, if you work in construction, you might want to claim the mileage allowance.

In this case, we’d recommend getting in touch with HMRC as soon as possible.

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