What is a P45 and What Do You Do With It?

Q: Is my employer legally required to give me a P45?

Yes. Under PAYE regulations, employers are legally required to issue a P45 on or before your last day of employment. If your employer refuses or fails to provide one, you can report this to HMRC. In practice, most employers now issue P45s electronically within a few days of your leaving date.

Q: What happens if I start a new job without a P45?

If you start a new job without a P45, your new employer will ask you to complete an HMRC Starter Checklist (formerly called a P46). Based on your answers, they apply a temporary tax code. Without a P45, you may be placed on an emergency code like 1257L M1 or BR, which could cause you to overpay tax until HMRC updates your code — usually within 4 to 6 weeks.

Q: Can I get a replacement P45 if I lose mine?

Your old employer cannot issue a duplicate P45 — HMRC regulations do not permit it. However, your old employer can provide a letter confirming your pay and tax details for the period, which most new employers accept in lieu. Alternatively, HMRC holds the data from your old employer and can confirm it. Ask your new employer to accept the HMRC Starter Checklist instead, which achieves the same practical result.

Changing jobs? Your P45 is the document that prevents you from being put on the wrong tax code. Here is what it contains, how to use it, and what to do if you do not have one.

What Is a P45?

A P45 is a document issued by your employer when you leave a job. Its official title is "Details of employee leaving work," and its core purpose is to tell both you and your new employer (or HMRC) exactly how much you have earned and how much tax you have paid in the current tax year up to your leaving date. This continuity of information is what allows the PAYE system to ensure you pay the correct cumulative amount of tax across all your jobs in a single tax year.

Without a P45, your new employer has no way of knowing whether you have already used your Personal Allowance, whether you have paid any tax at basic or higher rates, or whether you have any special tax code adjustments. The result is almost always an emergency tax code and overpaid tax.

The Four Parts of a P45

A P45 has four sections, each with a specific purpose:

Part 1 — Sent directly by your employer to HMRC electronically as part of the final payroll submission. You never handle Part 1 yourself.
Part 1A — Your copy. Keep this permanently — it is a record of your employment and may be needed for tax refund claims, benefit applications or historical income evidence years later.
Part 2 — Goes to your new employer. They use it to set up your tax records and apply the correct tax code from your first payslip.
Part 3 — Also goes to your new employer (or to the Jobcentre if you are claiming Universal Credit or Jobseeker's Allowance after leaving).

In practice, since most employers now issue P45s electronically through payroll software, the "parts" are often transmitted digitally rather than as paper documents. Your new employer may simply ask for your reference number or for the electronic file, depending on their payroll system.

What Information Does a P45 Contain?

A P45 includes:

Your full name and National Insurance number
Your date of leaving
Your final tax code at the date of leaving
Your total pay in the current tax year (6 April to leaving date)
Total income tax deducted year-to-date
Whether you were on a Week 1/Month 1 basis
Student loan deduction indicator (if applicable)
Your employer's PAYE reference

The year-to-date figures are crucial. If you earned £18,000 between April and August and then change jobs, your new employer can see from the P45 that you have already used £18,000 of the basic rate band and deducted the relevant portion of your Personal Allowance. Without this, they would start the count from zero and likely under-deduct or over-deduct tax.

What to Do With Your P45 When Starting a New Job

Hand Parts 2 and 3 to your new employer's HR or payroll team on or before your first day, if possible. The sooner they have it, the sooner your correct tax code is applied. If your new employer uses an online HR system, there is often a portal where you can upload the P45 document directly.

Your new employer will not need Part 1A — that is your own copy to retain. Never give away all copies of your P45; keep Part 1A permanently.

Starting a New Job Without a P45

If you do not have a P45 — perhaps because it has not been issued yet, because your previous employer has gone bust, or because this is your first job — your new employer will give you an HMRC Starter Checklist (formerly called a P46) to complete.

The Starter Checklist asks three key questions:

Statement A: This is your first job since 6 April and you have not been receiving taxable benefits or a state pension. Result: HMRC uses code 1257L on a cumulative basis (the most favourable option).
Statement B: This is your only job but you have had another job or taxable benefit since 6 April. Result: code 1257L on a Week 1/Month 1 basis.
Statement C: You have another job (in addition to this one). Result: code BR (basic rate, 20% on all income from this job with no personal allowance).

Choose the wrong statement and you will overpay or underpay tax. Statement A is often ticked incorrectly by people who did have a previous job in the same tax year. Always read carefully before signing.

Claiming Jobseeker's Allowance or Universal Credit

If you leave a job and make a claim for Universal Credit or Jobseeker's Allowance, take Parts 2 and 3 of your P45 to the Jobcentre instead of giving them to a new employer. This allows the DWP to calculate your claim correctly based on your income in the current tax year. If you later find a job while receiving benefits, the Jobcentre returns the relevant parts for your new employer.

Lost P45: What to Do

Your old employer cannot issue a duplicate P45 under HMRC rules — regulations state that only one P45 should exist per employment. However, there are practical workarounds:

Ask your old employer for a letter on headed paper confirming your leaving date, tax code, total pay and tax deducted. Most new employers accept this as an alternative.
Complete the HMRC Starter Checklist (Starter Declaration) — this achieves the same practical outcome for payroll purposes, even if it may result in an emergency code temporarily.
Log into your HMRC Personal Tax Account online — your employment history, pay and tax data is often visible there and can be used as supporting evidence.

How Long Does It Take to Get the Right Tax Code?

If you provide a P45, your new employer should apply the correct cumulative tax code from your very first payslip. If you are using the Starter Checklist or starting without a P45, it typically takes 4 to 6 weeks for HMRC to update your code and for the correction to flow through to payroll. Any overpayment during that period is automatically refunded through your subsequent payslips once the correct code is applied.

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Frequently Asked Questions

Is my employer legally required to give me a P45?

Yes. Employers are legally required to issue a P45 on or before your last day of employment. If they refuse or fail to provide one, you can report this to HMRC. Most employers now issue P45s electronically within a few days of your leaving date.

What happens if I start a new job without a P45?

Your new employer will ask you to complete an HMRC Starter Checklist. Based on your answers, they apply a temporary tax code. Without a P45, you may be placed on an emergency code like 1257L M1 or BR, which could cause overpayment of tax until HMRC updates your code — usually within 4 to 6 weeks.

Can I get a replacement P45 if I lose mine?

Your old employer cannot issue a duplicate P45 under HMRC rules, but they can provide a letter confirming your pay and tax details, which most new employers accept. Alternatively, completing the HMRC Starter Checklist achieves the same practical result for your new employer's payroll.