How to Pay Part-Time Employees UK: A Simple Guide

Part-time workers in the UK have the same employment rights as full-time colleagues — they are simply applied on a proportional basis. The Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 make it unlawful to treat a part-time worker less favourably than a comparable full-time worker without objective justification. In practice, many employers still get this wrong: miscalculating pro-rata holiday, mishandling bank holidays, failing to track actual hours for National Minimum Wage compliance, and forgetting that Statutory Sick Pay has its own eligibility threshold for low-hours workers.

This guide walks through every aspect of paying part-time employees correctly — from NMW compliance through to payslip obligations and parental leave rights.

National Minimum Wage for Part-Time Workers

The National Minimum Wage (NMW) and National Living Wage (NLW) apply to part-time workers in exactly the same way as full-time employees. There is no minimum-hours threshold — whether someone works 4 hours a week or 34, the same hourly rates apply. From April 2025, the rates are:

• Age 21+ (National Living Wage): £12.21 per hour
• Age 18–20: £10.00 per hour
• Under 18: £7.55 per hour
• Apprentices: £7.55 per hour

The most significant NMW risk for part-time workers is unpaid overtime. If a worker on 20 contracted hours regularly stays late or completes tasks in their own time, those additional hours count towards total hours worked. Divide total pay by total hours actually worked — not contracted hours — to establish the effective hourly rate. If it falls below the NMW threshold, you have a compliance breach.

Other common NMW pitfalls include deducting break time from pay when the break was not genuinely free time, rounding hours down at the end of a pay period, and forgetting that travel between work sites (but not travel from home to the first work location) counts as working time. Use our minimum wage calculator to check every pay period against the current thresholds.

Calculating Pro-Rata Holiday Entitlement

The statutory minimum holiday entitlement in the UK is 5.6 weeks per year, which includes bank holidays. For a full-time employee working 5 days a week, this equates to 28 days (5.6 × 5).

For part-time workers on a fixed weekly pattern, there are two correct methods depending on how the contract is expressed:

Method 1 — Days-based: Multiply 5.6 by the number of days worked per week.

Method 2 — Hours-based: Multiply 5.6 weeks by contracted weekly hours. This is more accurate when a worker does unequal day lengths.

The hours-based formula is generally preferred because it handles employees whose working days vary in length:

5.6 weeks × contracted weekly hours = annual leave entitlement in hours

Examples using a 37.5-hour full-time benchmark:

Worked example — 3-day week worker: Sarah works Monday, Wednesday, and Friday, 7.5 hours each day (22.5 hours per week). Her entitlement is 5.6 × 22.5 = 126 hours, or 16.8 days. If you round up (which you must — you cannot round down statutory entitlement), she is entitled to 17 days.

Worked example — 4-day week worker: James works Monday to Thursday, 7.5 hours per day (30 hours per week). His entitlement is 5.6 × 30 = 168 hours, or 22.4 days — round up to 23 days.

Use our pro-rata holiday calculator to generate the exact figure for any contracted pattern, or our leave entitlement calculator for mid-year starters and leavers. Our full step-by-step walkthrough is in the holiday entitlement guide.

Bank Holidays and Part-Time Workers

This is the most misunderstood area of part-time pay. Part-time workers are entitled to a pro-rata share of bank holidays — but they are not automatically entitled to every bank holiday that a full-time worker receives.

Consider a worker who only works on Mondays. The UK has eight bank holidays, and several of them — both May bank holidays, the late August bank holiday — fall on Mondays. A Monday-only worker will use a disproportionate share of their total entitlement on bank holidays compared with, say, a Tuesday–Thursday worker who may rarely encounter a bank holiday on a working day.

The principles under the Part-Time Workers Regulations 2000 are:

• A part-time worker whose working day falls on a bank holiday is entitled to the day off — and it counts against their annual leave allowance (or you give a substitute day instead).
• A part-time worker whose working days never coincide with bank holidays gets no automatic additional days off, but equally has no bank holidays eating into their leave balance.
• If a Monday-only worker ends up with more bank holidays than their pro-rata share would suggest (relative to a full-time worker), best practice is to offer substitute days or additional leave so the worker is not disadvantaged by which day of the week they work.
• You cannot simply tell a 3-day week worker they are entitled to 5 bank holidays out of 8 and leave it at that — you must look at which days they actually work and which bank holidays fall on those days.

Use our holiday calculator to work through bank holiday entitlement for different working patterns, including calculations for workers on non-standard days.

Overtime Thresholds and NMW Compliance

There is no legal obligation to pay a premium overtime rate to part-time workers until they have worked more hours than the equivalent full-time threshold — typically 37.5 to 40 hours per week depending on the contract. Hours between a worker's contracted part-time hours and the full-time threshold are legally payable at the standard rate only.

However — and this is critical for NMW compliance — all hours actually worked count when checking the minimum wage. If a part-time worker on 20 contracted hours stays late to finish a project and ends up working 25 hours in a week, all 25 hours must be used when calculating the effective hourly rate for NMW purposes. Paying only for 20 hours while the worker has actually worked 25 creates a National Minimum Wage breach that HMRC can investigate and penalise.

The key principle: every hour of work must be paid at no less than the NMW rate, whether it was contracted or not. Unpaid overtime for part-time workers is unlawful and one of the most common compliance failures small employers face.

Use our overtime pay calculator to model different hours scenarios and check what your part-time workers are owed.

Statutory Sick Pay (SSP) for Part-Time Workers

Statutory Sick Pay is not pro-rated for part-time workers. The weekly SSP rate from April 2025 is £116.75 per week regardless of whether the employee works 2 days a week or 4. A part-timer who qualifies receives the same flat weekly rate as a full-timer.

The important caveat is the Lower Earnings Limit (LEL). To qualify for SSP, workers must earn at least the LEL — which is £123 per week in 2025/26. For workers on very low contracted hours, their total weekly earnings may fall below this threshold, making them ineligible for SSP.

Example: An employee working 8 hours per week at the National Living Wage of £12.21/hour earns £97.68 per week — below the £123 LEL. They do not qualify for SSP. An employee working 12 hours per week at the same rate earns £146.52 per week — above the LEL, so they do qualify.

Note that you can always pay contractual sick pay above and beyond SSP — many employers with part-time staff choose to do so to avoid low-hours workers falling through the statutory safety net. Use our statutory sick pay calculator to check eligibility and amounts for your part-time workers.

Payslips and Record Keeping

Every employee (and, since April 2019, every worker — including part-time and zero-hours workers) has the right to an itemised payslip under section 8 of the Employment Rights Act 1996. The payslip must show:

• Gross pay
• Net pay
• Each deduction (tax, National Insurance, pension) listed separately
• Where pay varies by the amount of time worked, the hours to which the pay relates (this includes most part-time workers)

For part-time workers whose weekly hours vary, you must show the hours on the payslip. Failure to provide an itemised payslip is a breach of statutory rights and employees can bring a claim to an Employment Tribunal.

Record-keeping obligations: HMRC requires employers to keep payroll records for a minimum of 3 years from the end of the tax year to which they relate. However, best practice — and the recommendation of most employment solicitors — is to retain records for 6 years, in line with the Limitation Act 1980, to protect against late claims for unpaid wages, holiday pay, or NMW arrears.

Records that must be kept include: actual hours worked by each employee, gross and net pay, deductions made, and any records relevant to NMW compliance. For part-time workers, keeping records of actual versus contracted hours is particularly important — HMRC can (and does) investigate historic NMW compliance. Our small business time tracking overview explains how to implement compliant time records without complex software.

Parental Leave Rights for Part-Time Workers

Part-time workers have the same statutory entitlement to parental leave as full-time workers. The entitlement is not reduced because someone works fewer hours. Key statutory entitlements that apply equally include:

• Statutory Maternity Leave: 52 weeks (26 weeks Ordinary, 26 weeks Additional), regardless of contracted hours
• Statutory Maternity Pay (SMP): 6 weeks at 90% of average weekly earnings, then 33 weeks at the flat SMP rate (£184.03/week from April 2025) or 90% of average weekly earnings if lower — note this is based on actual earnings, so part-time workers will typically receive less SMP than full-time workers simply because their average weekly earnings are lower
• Statutory Paternity Leave: 1 or 2 weeks — the same entitlement applies regardless of hours worked
• Shared Parental Leave: Up to 50 weeks can be shared between parents, with the same eligibility rules applying to part-time workers as to full-time
• Parental Leave: 18 weeks of unpaid leave per child (up to age 18) — again, this is not pro-rated and applies in full to part-time workers

Use our maternity leave calculator to calculate SMP entitlement based on a part-time worker's actual average weekly earnings.

Common Mistakes Employers Make with Part-Time Pay

1. NMW breach from unpaid overtime

The most common and most expensive mistake. A part-timer on 20 contracted hours who works an average of 23 hours is effectively being underpaid if you only run payroll on 20 hours. When you divide their monthly pay by their actual hours, the effective hourly rate may fall below NMW. HMRC can investigate up to 6 years of historic records and will issue a Notice of Underpayment plus a penalty of up to 200% of the underpaid amount.

2. Using days instead of proportion for holiday

Simply giving a 3-day week worker 3/5 of 20 days (= 12 days) is wrong if the full-time entitlement includes bank holidays in the 20 days. The correct approach is: (contracted days ÷ 5) × 28 days = 16.8 days, not 12. Underpaying holiday entitlement by using days-only shortcuts is a common source of Employment Tribunal claims.

3. Forgetting bank holiday adjustment by working pattern

As described above, assigning a flat pro-rata share of bank holidays without checking which days the worker actually works can result in workers who always work on bank holiday days being disadvantaged. This breaches the Part-Time Workers Regulations.

4. Not issuing itemised payslips

Part-time and zero-hours workers are entitled to itemised payslips showing hours worked where pay varies. Failing to provide these is a statutory breach and employees can pursue it at tribunal without needing to pay a fee.

5. Using a single leave policy for all staff

A leave policy written for full-time employees (e.g., "you must take at least one week of holiday at a time") may be disproportionately onerous for a part-timer and could constitute less favourable treatment. Review your leave policies to ensure they work equitably for staff on reduced hours.

Frequently Asked Questions