What Is a Payroll Number and Where to Find It

Around 30.3 million people in the UK are paid through PAYE ^[7], and every one of them is entitled to a payslip from their first payday ^[3]. On most of those payslips sits a short code that confuses new starters and HR teams alike: the payroll number.

A payroll number, sometimes called a payroll ID, employee number or works number, is the unique reference an employer assigns to each person on its payroll. Employees need it for HR and pay queries; employers need it to keep PAYE records clean and to report pay to HMRC accurately under Real Time Information ^[15].

This guide explains what a payroll number is, where to find it, how it differs from the other identifiers that appear on UK payslips, and how employers should assign and manage payroll numbers to avoid duplicate records with HMRC.

Key takeaways

• A payroll number is a unique reference an employer assigns to each employee for identification within its payroll system.
• It usually appears on the payslip, and often on the P60 and P45 as well.
• It is not the same as a National Insurance number, which is issued by the government and follows the individual for life.
• HMRC does not issue payroll numbers; in RTI submissions the payroll ID can be up to 35 alphanumeric characters.
• Changing a payroll ID without flagging the change to HMRC is a known cause of duplicate employment records and incorrect tax codes.

What a payroll number is

A payroll number is an internal identifier. The employer creates it when an employee joins, and it identifies that person, and that specific employment, inside the payroll system ^[1]. Two employees with similar names are distinguished instantly by their payroll numbers, which is why payroll teams ask for the number whenever someone raises a pay query.

There is no legally mandated format. A small business might use simple sequential numbers (001, 002), while larger employers often combine letters and digits to encode a department or site, for example MW-0147. In HMRC's Real Time Information reporting, the equivalent data item, the payroll ID, can be any alphanumeric string up to 35 characters ^[10].

A payroll number is also employment-specific. An employee who leaves and later rejoins the same company will normally receive a new number, and someone holding two jobs with the same employer should have a distinct payroll ID for each employment ^[10]. Modern UK payroll software generates and tracks these identifiers automatically.

Where to find a payroll number

The payslip is the first place to look. Employers must give every employee and worker a written, itemised pay statement at or before payday under section 8 of the Employment Rights Act 1996 ^[2], and most payroll systems print the payroll number near the employee's name at the top of that statement ^[1].

The table below summarises the most common places a payroll number appears.

The P60 summarises pay and deductions for the tax year, and the P45 records pay and tax when an employment ends ^[5]. An employee who cannot locate any of these documents can simply ask the payroll team, and an employer can issue replacement information for lost forms, although a duplicate P45 cannot be reissued ^[12]. Guidance on year-end certificates is covered in more depth in the Moonworkers article on how to get a P60.

Payroll number vs the other numbers on a payslip

A UK payslip carries several identifiers, and they are frequently confused. Each serves a different purpose and is issued by a different party.

A National Insurance number is made up of 2 letters, 6 numbers and a final letter, and it stays with the individual for life ^[4]. The payroll number, by contrast, belongs to one employment with one employer and has no meaning outside that company. HMRC tracks individuals through the National Insurance number and the employer through the PAYE reference, never through the payroll number ^[14].

The employer PAYE reference follows a fixed pattern: a 3-digit tax office number, a forward slash, then the scheme reference, for example 123/AB456 ^[6]. Employers receive it when registering for PAYE, which must happen before the first payday ^[11]. Sole directors and very small employers running occasional payslips face the same registration rules, which is one reason an instant payslip service handles the HMRC references on the employer's behalf.

Why payroll numbers matter for RTI compliance

For employers, the payroll number is more than an internal convenience. Under Real Time Information, the payroll ID submitted on each Full Payment Submission identifies a single employment within the PAYE scheme ^[10]. HMRC's systems use it, alongside the employee's personal details, to match each payment to the right employment record.

Problems start when the payroll ID changes without warning, for example after switching payroll software. If the new system sends a different payroll ID without flagging it as a change, HMRC may create a duplicate employment record, which can trigger incorrect tax codes and inflated debt estimates for the employee ^[13]. The correct procedure is to submit the new payroll ID together with the old one and set the payroll ID change indicator on the FPS ^[10].

HMRC-recognised payroll software handles this matching logic automatically, carrying payroll IDs through software migrations and flagging changes on the next submission. For a growing business, this is one of the quiet reasons to choose payroll built for SMEs rather than managing references in a spreadsheet. The same discipline applies at API level: platforms that embed payroll through an HMRC-recognised payroll API must persist a stable payroll ID per employment across every FPS they generate. Employees who spot a missing or incorrect payroll number on a payslip should raise it with payroll promptly, as payslip errors can be escalated to an employment tribunal if unresolved ^[16].

Conclusion

The payroll number is the smallest identifier on a payslip and the easiest to overlook, yet it does precise work: it ties one person to one employment in one payroll system. It carries no legal weight with HMRC, where the National Insurance number and the employer PAYE reference do the heavy lifting, but it keeps internal records unambiguous and, through the RTI payroll ID, anchors the employment record HMRC holds.

As UK payroll becomes more automated and more deeply embedded inside HR and accounting platforms, identifier hygiene matters more, not less. Systems that generate, persist and reconcile payroll IDs correctly remove a whole category of duplicate-record errors before they reach HMRC.

Frequently asked questions

Is a payroll number the same as a National Insurance number?

No. A payroll number is assigned by the employer and only identifies the employee inside that company's payroll system. A National Insurance number is issued by the government, follows the format of 2 letters, 6 numbers and a final letter, and stays with the individual for their whole working life ^[4].

Where can an employee find their payroll number without a payslip?

The P60 and P45 usually show the payroll number, as do most online HR and payroll portals ^[5]. Failing that, the employer's payroll or HR team can confirm it directly. New starters can also check their employment contract or offer letter.

Do all UK employers have to issue payroll numbers?

No law forces an employer to use payroll numbers, but every employer must provide itemised payslips showing gross pay, deductions and net pay ^[2]. In practice, almost all payroll software assigns an employee reference automatically because RTI submissions work more reliably with a stable payroll ID ^[10].

Can a payroll number change, and does it matter?

It can change, typically when an employer switches payroll software or restructures its employee references. The change is safe only if the employer reports it properly on the next Full Payment Submission, sending the old and new payroll IDs together with the change indicator set. Skipping that step can create a duplicate employment record at HMRC and disrupt the employee's tax code ^[13].