P45 Tax Refund: How to Check if You Are Owed Money

Your P45 is the document your employer gives you when you leave a job. It plays a crucial role in making sure you pay the right amount of tax when you start a new job or if you stop working altogether. Getting your P45 right can be the difference between paying the correct tax and losing hundreds of pounds to HMRC unnecessarily.

What Is a P45?

A P45 is a form in three parts that your employer is legally required to give you when you leave their employment. It shows:

• Your tax code at the date of leaving
• Your total pay from that employment in the current tax year up to your leaving date
• The total tax deducted from that pay
• Your employer's PAYE reference
• Your National Insurance number
• The date your employment ended

Part 1 goes to HMRC. Parts 2 and 3 are for you. You give Part 2 and 3 to your new employer when you start a new job.

Why Your P45 Is So Important

Your P45 is the link between your old and new jobs in the PAYE system. When your new employer receives your P45, they know exactly how much you have earned and how much tax you have paid so far in the tax year. This allows them to calculate your tax correctly on a cumulative basis.

Without a P45, your new employer does not know your previous earnings or tax paid. They will either ask you to complete a starter checklist or, more commonly, put you on an emergency tax code. And as we know, emergency tax codes almost always result in overpayment.

Common P45 Tax Refund Scenarios

**You left a job and did not work for the rest of the tax year.** If you earned 20,000 pounds in 8 months and then stopped working, you will have paid tax based on an assumption that you would earn at that rate all year. But because you stopped, your total annual income is only 20,000 pounds. With a Personal Allowance of 12,570 pounds, you should only pay tax on 7,430 pounds. If you were taxed as though you would earn 30,000 pounds for the full year, you have overpaid.

**You started a new job but did not hand over your P45.** Your new employer puts you on an emergency tax code. You pay too much tax because the cumulative position from your old job is not carried over.

**You had a gap between jobs.** You left one job in June and started another in September. During July and August, you had no income but your Personal Allowance was still accumulating. If the new employer does not account for this (perhaps because you did not provide your P45), you could overpay.

**The dates on your P45 are wrong.** If your former employer made an error on your P45, the figures your new employer uses will be wrong, leading to incorrect tax calculations.

How to Check if You Are Owed a Refund

Take the figures from your P45 and work out whether the tax deducted was correct for the amount you earned. Here is the simple approach:

1. Look at the total pay and total tax figures on your P45

2. If you did not start another job that tax year, calculate the correct tax on just the P45 income

3. Compare the correct tax figure to the actual tax deducted shown on the P45

4. If the actual tax is higher, you are owed a refund

For a more precise calculation that accounts for your full circumstances, use the AuditMyTax calculator. You can upload your P45 and it will automatically calculate whether you overpaid based on the employment dates and tax year in question.

How to Claim a P45 Tax Refund

**If you are starting a new job:** Hand your P45 to your new employer. They will use the figures to calculate your tax correctly going forward. If you overpaid in the previous job, the cumulative PAYE system should automatically refund the excess through your new pay.

**If you are not working:** You can claim a refund directly from HMRC. You have three options:

1. Call HMRC on 0300 200 3300 with your P45 details and National Insurance number

2. Claim through your Personal Tax Account online

3. Write to HMRC at their PAYE address including your P45 figures

If the tax year has ended, HMRC may send you a P800 automatically. But do not wait for it - proactive claims are processed faster.

What If You Have Lost Your P45?

If you have lost your P45, contact your former employer and ask for the details. They cannot reissue the P45 itself, but they can provide you with the information on it (total pay, total tax, tax code, leaving date). You can then give these details to your new employer or to HMRC.

Your former employer is required to keep payroll records, so they should be able to provide the information even years later.

The 4-Year Rule

You can claim refunds related to P45 overpayments for the current tax year and the previous 4 years. In 2026, that means you can go back to the 2021/22 tax year. If you left a job in 2022 and never checked whether you overpaid, now is the time to look into it before the window closes.

Key Advice

Never throw away your P45. It is one of the most important tax documents you will receive. When you leave a job, keep it safe and give it to your next employer as soon as possible. If you are not starting a new job, use the P45 figures to check whether you have overpaid tax. A few minutes of checking could put hundreds of pounds back in your pocket.