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

We've updated this guide on 6th August 2019

A P800 form, also known as a tax calculation, is a letter that HMRC will send you when they think that you have not paid the right amount of tax:

  • either too little
  • or too much tax.

What if I think that my P800 form is wrong?

It can happen – P800s aren’t always correct.

What you need to do:

  1. Compare it with your P60P45, 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.

What can happen:

  • 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
  • or 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?


What you need to do:

  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 finished, you should receive the rebate to your bank account in about 5 days.

By phone

You can also call HMRC on 0300 200 3300.

Wait for a cheque

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

What if my P800 says I owe tax?

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

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?

Short answer: yes.

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

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

Let us know if you need help.

Need help with your tax return?

Get your self assessment prepared for you online by certified accountants for £119

Online self assessment preparation assisted by professional accountants

How TaxScouts works

Simple online tax assessment

1. Simple online tax assessment

Our online tax-bot will go over your tax situation and will make sure you won’t overpay your taxes.

Chat to human advisors

2. Chat to human advisors

You can talk to one of our tax assistants at any time during the process when you have any questions.

We’ll sort your documents online

3. We’ll sort your documents online

We’ll tell you exactly what documents you need and sort them for you online. You just upload them or snap a picture with your phone.

Everything gets prepared for you

4. Everything gets prepared for you

Your certified accountant will go over your details & prepare your tax return for you to review. It will be filed on your behalf once you approve it.

"Very fast"
Very fast and gave good advice I will be using every year
Wayne L
"I was very sceptical hitting the pay…"
…but my accountant did absolutely everything and took all of the hassle out of doing a tax return.
Wesley Thompson
"Absolutely amazing service"
I've been worrying about my tax return for weeks and I'm so pleased I contacted TaxScouts. Outstanding service and problem solved.
Sandra S

Who our service is for

First time tax filers

We have a simple online service that guides you through the entire process. Regardless of your reasons for doing your tax return we'll help you get it done right.

Construction workers

We'll prepare your self assessment and help to maximise your CIS tax refund. We have the lowest fees in the industry and you don't have to pay up front if you're eligible for a refund.

People living overseas

Our service allows people living abroad to prepare their income tax return online. We are able to process all returns regardless of your current country of residence.

Company directors

UK company directors are required to file their self assessment annually. TaxScouts handles this through a simple online process.


Long Lets, Airbnb, Capital Gains. TaxScouts will sort out your self assessment and take away the worry of tracking all the recent tax changes.


TaxScouts ensures the self employed don't overpay on their taxes. We'll help you benefit from all the tax breaks and deductions that can be applied to your return.

And for everyone else who needs to do their self assessment

At TaxScouts we appreciate that tax returns are highly individual. Before you get assigned an accountant we make sure to understand your circumstances and help you build your optimal tax profile.

Let's start by creating your account

What happens next

  • We'll ask you a couple of short questions
  • Then we'll tell you what documents we need
  • Finally one of our qualified accountants will file your tax return