A lost P45: what to do when none can be reissued
A P45 is a one-time document, and HMRC is explicit that a replacement cannot be issued once the original has been produced [1]. That single rule shapes every answer to a lost P45: the route is never a reprint, it is the starter checklist, the form a new employer uses to set the right tax code without the missing paperwork [2].
The P45 records pay and tax from 6 April to the date a job ends, along with the tax code in use, and an employee hands it to their next employer so PAYE continues without interruption [3]. Lose it, and the worry is usually about being taxed incorrectly in a new job. That worry is manageable, because the checklist does the same work and any short-term overpayment is recoverable.
This article explains why no duplicate exists, how the starter checklist replaces a P45, how the starter declaration sets the opening tax code, and how emergency tax is avoided or reclaimed.
Key takeaways
- A lost P45 cannot be replaced; HMRC does not allow a former employer to reissue one [1].
- The starter checklist takes the place of a P45 and lets a new employer work out the correct tax code [2].
- The starter declaration, A, B or C, decides the opening tax code and the basis of calculation [4].
- Emergency tax from a missing P45 is temporary, and any overpayment is refunded once HMRC issues the right code [5].
Why a P45 cannot be replaced
The P45 is issued once, at the point an employee leaves, and the rules treat it as a single original rather than a record an employer can print on demand [1]. This is the key difference from a P60, which an employer can reissue as a copy marked 'Duplicate' [6]. For a P45, there is no equivalent duplicate process.
That does not mean the information is gone. The pay and tax figures the P45 carried were reported to HMRC when the employee left, so the data still exists; it is only the specific multi-part form that cannot be produced a second time [3]. The practical answer, then, is never to chase a reprint but to give the new employer the information another way.
The starter checklist: the replacement that is not a P45
When a new starter has no P45, the employer uses a starter checklist to collect the details needed for payroll and to determine the opening tax code [2]. The form replaced the old P46 and is designed to do the same job as a P45 for the new employer's purposes, so the absence of the original need not delay correct PAYE [4].
The checklist should be completed and handed to the employer as soon as possible, ideally before the first payday, because the employer needs it to report the new starter to HMRC and apply the right code from the first pay run [2]. A National Insurance number is part of the information required to start the job [4].
The starter declaration sets the tax code
The heart of the checklist is the starter declaration, a choice between three statements that maps directly to a tax code and a calculation basis [4]. The table below sets out the three options and what each produces.
| Declaration | Situation | Resulting tax code |
|---|---|---|
| A | This is the first job since 6 April, with no other income or taxable benefits | Standard cumulative code (1257L) [[7]](https://www.gov.uk/tax-codes/what-your-tax-code-means) |
| B | This is the only job, but there has been other employment or taxable benefit since 6 April | Standard code on a week 1 / month 1 basis [[8]](https://www.gov.uk/tax-codes/emergency-tax-codes) |
| C | There is another job or pension running alongside this one | Code BR, basic rate on all pay with no allowance [[7]](https://www.gov.uk/tax-codes/what-your-tax-code-means) |
Declaration A is the most favourable, giving the full personal allowance from the first payday. Declaration C is the most restrictive, taxing all earnings at basic rate because the allowance is assumed to be used by the other job [7]. Where the right choice is unclear, the cautious default is declaration B, which protects against a large underpayment building up [4].
Emergency tax: why it happens and how it ends
Without a P45 or a completed checklist, an employer has too little information to apply a cumulative code, so a new starter is often put on an emergency code at first [8]. An emergency code is 1257L followed by W1, M1 or X, and it works out tax on each pay period in isolation rather than across the year to date [8].
The effect is usually temporary. Once HMRC has the information to issue the correct code, deductions adjust, and any tax overpaid while on the emergency code is refunded through later pay [5]. Completing the starter checklist promptly is the fastest way to shorten the time spent on an emergency code [2].
If a P45 turns up after the first payday, it can still be handed over. The employer uses the late P45 to recalculate the code where HMRC has not already sent one, so the figures fall back into line [9]. Where HMRC has already issued a code, that code is used instead of the late P45 [9].
When the figures themselves are needed
Sometimes the concern is not the new job but proof of the pay and tax the P45 recorded, for a tax refund claim or a Self Assessment return. Those figures sit with HMRC and can be reached without the form. A personal tax account shows pay and tax by employer for the current and previous five years [10], and HMRC issues a statement of employment history for a formal record [11].
For income evidence in particular, the P45 is rarely the only acceptable document. A year-end P60 or HMRC's own records often serve just as well, and a reader weighing income proof for a property purchase can follow the guide on using a P60 for a mortgage or the wider walkthrough on how to get a P60.
What this means for employers running payroll
An employer rarely needs to worry about a lost P45, because the process is built around the alternative. The duty is to collect a starter checklist where no P45 is presented, apply the resulting tax code, and report the new starter to HMRC by the first payday [4]. An employer should never try to issue a duplicate P45 for a leaver, since the form is produced only once [1].
Getting the starter declaration right at this stage matters, because an incorrect declaration is a common cause of a new employee landing on the wrong code and either overpaying or building up an underpayment [8]. Most modern UK payroll software maps each declaration to the correct code and calculation basis automatically, which is why the choice on the checklist is the only judgement an employer has to make. Records of the checklist and the codes applied must be kept for at least three years after the relevant tax year [12].
Bureaux and embedded payroll
Accountants onboarding starters across many client schemes handle the same logic at scale, and a payroll platform built for bureaux flags the declaration and code per employee rather than per firm [4]. Platforms that build payroll into their own products apply the declaration-to-code mapping programmatically through an HMRC-recognised payroll API, so a missing P45 never stalls a first pay run [8]. In both cases the starter checklist, not a reissued P45, is what keeps PAYE accurate from day one.
Conclusion
A lost P45 is far less of a problem than it first appears, because the system never relied on a reprint. The starter checklist gathers the same details, the starter declaration sets the opening tax code, and emergency tax, where it arises at all, is temporary and refunded. The pay and tax figures the P45 once held remain available through HMRC for any other purpose.
The wider shift is away from the paper form and towards the data behind it. As starter information flows to HMRC in real time and personal tax accounts hold the historic figures, the P45 is becoming a convenience rather than a single point of failure, and a lost copy is rarely the obstacle it used to be.
Frequently asked questions
Can a former employer reissue a lost P45?
No. HMRC does not allow a replacement P45 to be produced once the original has been issued, because it is treated as a single document rather than a record an employer can reprint. The information it carried was already reported to HMRC when the employee left, so it is not lost. To start a new job, the employee completes a starter checklist instead, which gives the new employer everything needed to apply the right tax code.
What is a starter checklist and when is it used?
A starter checklist is the form a new employee completes when they do not have a P45 to hand to a new employer. It collects personal details, the National Insurance number and a starter declaration, which together let the employer work out the opening tax code and report the new starter to HMRC. It replaced the old P46 and does the same job as a P45 for the new employer's purposes.
Why does a missing P45 sometimes cause emergency tax?
Without a P45 or a completed starter checklist, an employer lacks the information to apply a cumulative tax code, so a new starter may be placed on an emergency code that taxes each pay period in isolation. This can mean paying slightly more tax at first. The code corrects once HMRC has the right information, and any overpayment is refunded through later pay, so completing the checklist quickly shortens the time on an emergency code.
How can the pay and tax figures from a lost P45 be retrieved?
The figures are held by HMRC even though the form cannot be reissued. A personal tax account shows pay and tax by employer for the current and previous five years, and HMRC can provide a formal statement of employment history for a written record. For income evidence, a P60 or HMRC's own records are usually accepted in place of a P45, so the missing form rarely prevents proof of earnings.
