What happens when you start a new job without a P45

Plenty of people leave a job and never receive their P45. The employer might have gone quiet, closed down, or simply be slow with paperwork. Starting a new job without this form can feel worrying, especially when you see an unfamiliar tax code on your first payslip.

The good news is that you are not stuck. The tax system is designed to cope when a P45 is missing, and any overpaid tax can be corrected. This article explains what the P45 is for, what your new employer must do, how emergency tax works and how refunds are handled, using only official and verified sources.

What a P45 actually is and why it matters

A P45 is a document your employer must give you when you stop working for them. It shows:

• how much tax you have paid on your salary so far in the tax year
• your total pay to date in that job
• your tax code and leaving date

HMRC’s workers’ guide confirms that you get a P45 when you leave a job and that it shows tax paid so far in the tax year.
Source: https://www.gov.uk/paye-forms-p45-p60-p11d

Your new employer normally uses this form to:

• set you up on their payroll
• continue the correct tax code
• avoid double-taxing income you have already paid tax on

What if your old employer never sends the P45?

Employers are required to issue a P45 when employment ends. HMRC’s employer guide states that employers must give a P45 when an employee stops working and should use payroll software to produce it.
Source: https://www.gov.uk/get-paye-forms-p45-p60

In reality, you might not get it because:

• the business has closed or gone insolvent
• the payroll provider is slow or disorganised
• there is a dispute with management
• your contact details are out of date

There is an important reassurance here: you are not penalised if your employer fails to issue the form. HMRC deals with the missing information in other ways.

What your new employer should do instead

If you do not have a recent P45, your new employer must follow HMRC’s “new employee” guidance.

HMRC says that if you do not have a P45, the employer must ask you to complete a starter checklist (which replaced the old P46).
Source: https://www.gov.uk/new-employee

The starter checklist:

• collects information about your circumstances
• asks whether you had another job in this tax year
• asks about student loans
• helps the employer decide which starter statement applies

HMRC also publishes the starter checklist form itself, which explicitly says it is used when an employee does not have a P45.
Source: https://assets.publishing.service.gov.uk/media/6331a05f8fa8f51d29278ebc/Starter_checklist.pdf

Your new employer uses this information to set up your payroll and send the first real time information (RTI) submission to HMRC.

Emergency tax codes and why they are not a penalty

Without a P45, many people are put on what is called an emergency tax code.

HMRC explains that emergency tax codes are used when they do not have up-to-date details of your income, for example when you start a new job and your employer does not have your P45.
Source: https://www.gov.uk/tax-codes

You may see codes such as:

• 1257L W1 or M1
• 0T
• BR

These codes can temporarily reduce your take-home pay because:

• they may not give you your full personal allowance
• all your income might be taxed at a basic or higher rate until HMRC has full information

However, an emergency code is not a fine or punishment. It is a temporary setting to make sure some tax is collected until the system has a complete picture of your income.

HMRC’s tax code guidance confirms that codes change when HMRC receives more accurate information from employers.
Source: https://www.gov.uk/tax-codes/how-to-update-your-tax-code

How HMRC corrects things without a P45

Even without a P45, HMRC still receives details of your pay and tax through RTI every time your employer runs payroll.

HMRC’s tax-code guidance explains that:

• employers send pay and tax details electronically
• HMRC uses this information to work out whether your code is correct
• HMRC updates your tax code and informs your employer if it needs changing
  Source: https://www.gov.uk/tax-codes

When your new employer sends the first payroll submission using your starter checklist details, HMRC can:

1. match your National Insurance number
2. identify previous income and tax in the same tax year
3. adjust your tax code
4. send an updated code to your employer

Your employer must then apply the new code on the next payroll run, which can increase your take-home pay and begin to correct any over-deduction.

You can see your current tax code and the reason it changed by using HMRC’s “Check your Income Tax” online service.
Source: https://www.gov.uk/check-income-tax-current-year

What if you think you have overpaid tax?

If a missing P45 and emergency tax code mean you have paid too much tax, HMRC can refund it.

There are two main ways this happens:

1. Automatic correction within the year
   When HMRC updates your code, your employer’s payroll can adjust for overpayments in later payslips.

2. Refund after the tax year
   If the year has already ended, HMRC may send you a tax calculation (for example a P800) and pay a refund, or you can check how to claim a refund.
   Sources:

   • https://www.gov.uk/claim-tax-refund
   • https://www.gov.uk/tax-overpayments-and-underpayments/if-youre-due-a-refund

You are allowed to claim back overpaid tax, and HMRC’s refund guidance explains the process in detail.

What to do if your old employer is unresponsive

If you left a job and the employer will not send a P45, or you suspect it was never produced, you can:

1. Ask once in writing
   Email or write to the employer or payroll department so you have a record that you requested it.

2. Stop chasing indefinitely
   HMRC’s guidance for lost PAYE forms states that you cannot get a replacement P45, and that your new employer should use a starter checklist when a P45 is not available.
   Source: https://www.gov.uk/paye-forms-p45-p60-p11d/lost-paye-forms

3. Focus on your new job and current tax code
   Use the HMRC online service or app to check your code is correct and up-to-date.
   Source: https://www.gov.uk/check-income-tax-current-year

You are not fined or penalised simply because your previous employer failed to issue the form.

When should you be concerned?

You should pay attention if:

• your pay seems much lower than expected
• your tax code looks unusual (for example 0T or BR)
• the code has changed and you do not understand why

In that case:

• check your code online and read the explanation
• contact HMRC if the information looks wrong
• give your new employer accurate details via the starter checklist

HMRC’s tax code pages explain that you can use the online service to update employment details and correct an incorrect tax code.
Source: https://www.gov.uk/tax-codes/how-to-update-your-tax-code

Key points to remember

• Employers must give a P45 when you leave, but many people never receive it.
• If you do not have a P45, your new employer must use a starter checklist instead.
• An emergency tax code is a temporary safeguard, not a punishment.
• HMRC uses payroll submissions to rebuild your income record and update your tax code.
• Any overpaid tax can be refunded automatically through payroll or via HMRC’s refund process.
• You are not punished because a previous employer failed to send a form, but you should monitor your tax code and correct it if something looks wrong.

Knowing these rules means you can start a new job with more confidence, even if the paperwork from your last employer never arrives.