If you’ve ever looked at your payslip and wondered what is a payroll number, you’re not alone. Payroll numbers are commonly used in the UK payroll system, yet many employees and even small business owners don’t fully understand what they are, why they exist, or whether they are legally required.

This guide explains what a payroll number is, how it’s used in payroll processing, whether HMRC requires it, and what to do if you don’t have one. Whether you’re an employee checking your payslip or an employer running payroll, this article will give you complete clarity.

What Is a Payroll Number?

A payroll number is a unique reference number assigned to an employee by an employer to identify them within the payroll system.

It helps employers:

  • Track employee pay records

  • Process salaries accurately

  • Manage PAYE, National Insurance, and pension data

  • Distinguish between employees with similar names

A payroll number is internal to the employer and is not issued by HMRC.

Is a Payroll Number the Same as a National Insurance Number?

No. This is a common misunderstanding.

Payroll Number vs National Insurance Number

Payroll Number National Insurance Number
Assigned by employer Issued by HMRC
Internal reference Legal tax identifier
Can change Stays with you for life
Not mandatory Mandatory for tax

Your National Insurance number is used by HMRC to track your tax and benefits, while your payroll number is used by your employer to manage payroll records.

Where Can You Find Your Payroll Number?

You can usually find your payroll number on:

  • Your payslip

  • Your P60

  • Your P45

  • Payroll correspondence from your employer

It may appear as:

  • Payroll No

  • Employee No

  • Emp Ref

  • Staff ID

If you cannot find it, your employer or payroll department can provide it.

Why Do Employers Use Payroll Numbers?

Employers use payroll numbers to keep payroll records organised and accurate, especially when managing multiple employees.

Key Reasons Payroll Numbers Are Used

  • To avoid confusion between employees

  • To link payroll software records

  • To manage PAYE submissions

  • To track salary history

  • To handle statutory payments (SSP, SMP, etc.)

For businesses using payroll software, payroll numbers are often generated automatically.

Is a Payroll Number Required by HMRC?

No, HMRC does not legally require a payroll number.

However:

  • HMRC recommends consistent employee identifiers

  • Payroll numbers are included in RTI (Real Time Information) submissions if used

  • Once assigned, the same payroll number should be used consistently

If an employee does not have a payroll number, HMRC systems can still function using the National Insurance number and personal details.

Do All Employees Have a Payroll Number?

Not always.

An employee may not have a payroll number if:

  • The employer has a very small workforce

  • Payroll is managed manually

  • The employer chooses not to use payroll numbers

  • The employee has just started and payroll is not finalised

This does not affect the employee’s tax position.

What Happens If You Change Jobs?

Payroll numbers do not transfer between employers.

Each time you start a new job:

  • Your new employer may assign a new payroll number

  • Your previous payroll number becomes irrelevant

  • Your National Insurance number remains the same

This is normal and does not impact your tax record with HMRC.

Payroll Numbers and PAYE

Under the PAYE system, employers must report employee pay details to HMRC using Real Time Information (RTI).

A payroll number:

  • Helps match employee records

  • Is included in FPS submissions if used

  • Must remain consistent for that employment

Changing a payroll number unnecessarily can cause confusion in HMRC records.

Payroll Numbers for Multiple Jobs

If you have more than one job, you will usually have:

  • A different payroll number for each employer

  • Separate PAYE records for each employment

This does not mean you pay tax incorrectly; HMRC consolidates your records using your National Insurance number.

Payroll Number on P60 and P45 Explained

P60

  • Shows your payroll number for that tax year

  • Summarises total pay and tax deducted

P45

  • Shows payroll number for the employment you are leaving

  • Helps your next employer apply the correct tax code

If your payroll number is missing, HMRC can still process the information.

What If Your Payroll Number Is Incorrect?

An incorrect payroll number can cause:

  • Duplicate employee records

  • RTI mismatches

  • Payroll reporting issues

If you spot an error:

  1. Contact your employer or payroll provider

  2. Ask them to correct the payroll record

  3. Ensure future submissions use the correct number

Employers should avoid changing payroll numbers unless absolutely necessary.

Payroll Numbers for Employers: Best Practice

For employers, good payroll number practices include:

  • Assigning unique payroll numbers

  • Keeping payroll numbers consistent

  • Avoiding reusing old payroll numbers

  • Aligning payroll records with PAYE submissions

This reduces the risk of HMRC queries and payroll errors.

Is a Payroll Number the Same as an Employee Number?

In most cases, yes.

Many employers use the term employee number instead of payroll number. Both usually refer to the same internal reference used in payroll and HR systems.

Payroll Numbers and GDPR

Payroll numbers are considered personal data when linked to an identifiable employee.

Employers must:

  • Store payroll records securely

  • Limit access to payroll data

  • Comply with GDPR requirements

Using payroll numbers helps reduce exposure of sensitive data like National Insurance numbers.

Do Self-Employed People Have Payroll Numbers?

No.

Self-employed individuals:

  • Do not receive payroll numbers

  • Are not paid via PAYE

  • Manage tax through Self Assessment

Payroll numbers only apply to employees.

Payroll Numbers and Outsourced Payroll Services

If payroll is outsourced:

  • The payroll provider assigns or manages payroll numbers

  • Employers still remain responsible for accuracy

  • Consistent payroll data is essential for compliance

Professional payroll services help prevent errors and ensure RTI compliance.

When Should You Speak to an Accountant or Payroll Specialist?

You should seek professional advice if:

  • Payroll records are inconsistent

  • Employees are duplicated in payroll systems

  • HMRC queries arise

  • You are setting up payroll for the first time

Working with experienced accountants in Harrow ensures payroll is compliant, efficient, and stress-free for both employers and employees.

Frequently Asked Questions About Payroll Numbers

Is a payroll number mandatory?

No, but it is commonly used for payroll organisation.

Can two employees have the same payroll number?

No. Payroll numbers should always be unique within a company.

Does a payroll number affect tax?

No. Tax is calculated using PAYE and National Insurance numbers.

Can my payroll number change?

It can, but it’s best practice to keep it consistent for each employment.

Final Thoughts: What Is a Payroll Number and Why It Matters

Understanding what a payroll number is helps both employees and employers navigate the payroll process with confidence. While it’s not a legal requirement, it plays an important role in payroll administration, PAYE reporting, and record-keeping.

Used correctly, payroll numbers simplify payroll management, reduce errors, and support accurate reporting to HMRC. Whether you’re running a business or reviewing your payslip, knowing how payroll numbers work is essential.