Agency work suits a lot of people — flexible assignments, a foot in the door with good employers, and pay that can be perfectly fair. But agency pay has its own rulebook, and the chapter that matters most is the Agency Workers Regulations 2010. After 12 weeks with the same hirer, you are entitled to the same basic pay and conditions as someone hired directly to do the same job. Pro rata is the mechanism that makes that promise real: your pay is scaled to your hours, never discounted because you arrived through an agency.
This guide walks through how those rights work in practice — the 12-week clock, how to compare your rate with a permanent comparator, holiday accrual, overtime parity, the umbrella-company trap, and the payslip checks that catch problems early. All figures use worked examples so you can see exactly what “equal treatment” is worth in pounds.
The Agency Workers Regulations 2010, in plain English
The Regulations give agency workers two tiers of rights. From day one, you are entitled to be told about relevant job vacancies at the hirer and to access shared facilities such as the canteen, childcare, and transport services. After a 12-week qualifying period with the same hirer, you gain the right to equal treatment in basic working and employment conditions — pay first among them.
The 12-week clock runs on calendar weeks in which you do any work for the hirer, and it keeps running if you change agencies but stay with the same hirer. Short breaks (under six weeks) and breaks for sickness, holidays, or shutdowns generally pause rather than reset the clock. A break of six weeks or more between assignments with the same hirer starts a fresh clock — which is why an assignment mysteriously ending in week 11 deserves a hard look (more on that below).
What “equal treatment” actually covers
After 12 weeks, the agency must ensure your terms are no less favourable than those of a comparable directly-hired employee — the “comparator”. That is typically someone doing broadly similar work at the same hirer, with similar skills and qualifications. Equal treatment covers:
- Pay — basic hourly or salaried rate, overtime rates, shift and unsocial-hours allowances, and performance-related bonuses linked to the work itself
- Working time — the length of the working week, night work limits, and rest periods and breaks
- Annual leave — the same holiday entitlement, including how bank holidays are treated
It does not cover occupational sick pay, company pension schemes (auto-enrolment duties still apply separately), redundancy pay, or notice periods. Those remain governed by your contract with the agency. But on the core question — what you are paid per hour for the work you do — the rule after 12 weeks is parity, full stop.
Worked example 1 — the week-12 pay uplift
You are placed as a warehouse operative at £11.80 an hour. After a few weeks you learn the hirer pays its directly-employed operatives £13.90 an hour for the same shifts.
- Hourly shortfall after 12 weeks: £13.90 − £11.80 = £2.10
- On a 37.5-hour week: £2.10 × 37.5 = £78.75 a week
- Over a further 6 months on assignment: roughly £2,047 you are legally owed
The uplift should appear automatically from week 13 — you should not have to ask for it, though in practice many workers do. Keep every payslip from the assignment, because the before-and-after comparison is your evidence if the agency drags its feet.
Holiday pay, accrual and bank holidays
Agency workers accrue the statutory minimum of 5.6 weeks’ paid holiday a year, pro rata to hours worked. Because agency hours vary, holiday is usually tracked as it accrues — the standard accrual formula is:
Hours worked × 12.07% = holiday hours accrued
(12.07% is 5.6 ÷ (52 − 5.6): the statutory weeks expressed as a share of working weeks.) Crucially, once you pass 12 weeks, that holiday must be paid at the equal-treatment rate — the comparator’s rate, not your old agency rate.
Worked example 2 — holiday accrual at the parity rate
Using the warehouse example above (£13.90 parity rate), you work 150 hours over four weeks:
- Holiday accrued: 150 × 12.07% = 18.1 hours
- Value at the parity rate: 18.1 × £13.90 = £251.59
Two things to insist on. First, holiday pay should be paid when you actually take the leave — “rolled-up” holiday pay folded into your hourly rate so you never see a separate holiday payment is not the compliant way to do it. Second, check how bank holidays are handled: if directly-employed comparators get bank holidays off paid on top of their 28 days, you are entitled to the pro rata equivalent; if bank holidays come out of the 28 days for them, the same applies to you. Either way, the treatment must match.
Overtime parity: the same rates, the same access
Equal treatment extends to overtime — both the rate and access. If comparators earn time-and-a-half after 37.5 hours, so do you from week 13. And the hirer cannot quietly exclude agency staff from the overtime rota while offering extra shifts to permanent employees doing the same job; that is a difference in working conditions, and the Regulations bite on it.
Worked example 3 — an overtime week at parity
Back to our £13.90 comparator rate, with overtime at time-and-a-half (£20.85) after 37.5 hours. You work a 42-hour week after qualifying:
- Standard hours: 37.5 × £13.90 = £521.25
- Overtime: 4.5 × £20.85 = £93.83
- Correct total: £615.08
If the agency paid all 42 hours at a flat £13.90, you would get £583.80 — a shortfall of £31.28 for that one week. Multiply that across every overtime week of a long assignment and it becomes serious money. Always check whether your contract mentions overtime rates separately; silence on the point does not mean parity does not apply.
Umbrella vs PAYE: read the headline rate carefully
Many agencies offer a choice: be paid PAYE through the agency, or through an umbrella company. The umbrella headline rate almost always looks higher — say £16.00 an hour against £13.90 PAYE. That gap is not a bonus. The umbrella rate has to fund the employer’s costs that a PAYE engagement handles separately: employer’s National Insurance, the apprenticeship levy, employer’s pension contributions, and the umbrella’s margin.
Worked roughly: on a £16.00 umbrella rate, once employer’s NI (15% on earnings above the threshold), levy, pension and margin are accounted for, the take-home-equivalent rate frequently lands below the straight PAYE comparator rate. The Regulations still apply to umbrella engagements — your right to equal treatment after 12 weeks does not vanish because a third company sits in the chain — but the comparison gets murkier, which is precisely why some agencies prefer it.
Before choosing, the agency must give you a Key Information Document setting out the pay rate, deductions, and who bears the employer’s costs. Read it line by line, compare the true like-for-like hourly figure, and be wary of anyone who cannot explain the maths clearly.
Payslip checks every agency worker should run
- The week-13 uplift. Compare your hourly rate before and after the 12-week mark. If nothing changed and you know the comparator rate is higher, raise it in writing.
- Holiday shown separately. Holiday pay should appear as its own line when leave is taken — not silently rolled into the hourly rate.
- No employer costs deducted from your pay. Employer’s National Insurance and the apprenticeship levy are the engager’s liability. If your payslip shows them coming out of your gross, something is wrong.
- Hours match your timesheets. Keep your own record of every shift. Rounding “down to the nearest” anything is not a thing.
- The right tax code. Agency workers are frequently put on emergency tax when starting — check it, and reclaim any overpaid tax if the code was wrong.
Sanity-check your numbers
Pro rata calculations come up constantly in agency work — scaling a comparator’s salary to your hours, checking holiday accrual, or confirming an overtime week. A free pro rata salary calculator handles the proportioning in seconds, which makes it a handy second opinion before you query a payslip with the agency.
Frequently asked questions
Does the 12-week clock reset if I switch agencies but stay with the same hirer?
No. The clock follows the hirer, not the agency. Moving from one agency to another mid-assignment does not restart your qualifying period, and agencies cannot use a paperwork shuffle to dodge equal treatment.
What if there is no direct employee doing the same job to compare with?
The Regulations still apply — the agency and hirer must establish what the terms would be for a comparable direct recruit, looking at similar roles, pay grades, and collective agreements at the hirer. “No comparator” is not a get-out clause.
Can the hirer just end my assignment in week 11 to avoid equal pay?
Ending or structuring assignments specifically to prevent the 12-week right from arising is unlawful under the Regulations’ anti-avoidance provisions, and tribunals can impose additional financial penalties where they find it. A pattern of 11-week assignments at the same hirer is exactly the kind of evidence that matters.
Do the Regulations apply if I am paid through an umbrella company?
Yes. The equal-treatment right applies regardless of whether you are PAYE with the agency or engaged via an umbrella. The umbrella structure changes how pay is administered, not the underlying right to parity after 12 weeks.
How do I complain if my agency will not apply equal treatment?
Raise it with the agency in writing first, setting out your start date, the comparator rate, and what you are owed. If that fails, you can bring a claim in the Employment Tribunal — but go through Acas early conciliation first, as the law requires. Keep every payslip, timesheet, and contract: tribunal cases are won on paperwork.