Roughly 1.1 million people in the UK were on zero-hours contracts at the start of this year, according to the Office for National Statistics' Labour Force Survey - retail, hospitality, care work and warehousing account for most of them. The Employment Rights Act 2025 promised to end the worst of it, and the guaranteed-hours provisions are now working their way into contracts through 2026. What's actually landing on payslips, though, is narrower than the campaign slogans suggested, and knowing the gap between the two is worth understanding before you assume your rota is about to become predictable.
What "guaranteed hours" actually requires
The core mechanism is a right to be offered a contract reflecting the hours you've regularly worked over a defined reference period, once that pattern has held for long enough. Employers must calculate an employee's typical hours over a rolling reference window and then offer a contract that matches that pattern - not the number written on the original zero-hours agreement, and not a number the employer picks unilaterally. If you've been working 22 hours a week on average for months on a contract that technically says "zero hours guaranteed", your employer now has an obligation to formalise something closer to those 22 hours, not simply carry on treating the paperwork as accurate.
The right isn't automatic in the sense of arriving without paperwork. Workers still need to be offered the new contract by the employer at the end of the reference period - the trigger is on the employer's side, but it isn't optional once the qualifying pattern exists. Where this gets messy in practice is reference periods that straddle a quiet patch: a care worker whose hours dropped for six weeks because a regular client was in hospital may see their averaged hours pulled down enough to miss a threshold they'd have cleared in a normal month, and there's no simple appeal mechanism written into the current guidance for that kind of one-off dip.
Short-notice shift changes: what you're owed now
- Reasonable notice of shifts, with the length of "reasonable" varying by sector and being tested through early tribunal cases rather than fixed at a single number
- Compensation when a shift is cancelled or shortened at short notice, calculated against the hours you would have worked
- The right to refuse a shift offered with less than the applicable notice period, without that refusal being held against you at your next review
- And, for many workers, the simple fact that a manager can no longer post next week's rota on a Thursday evening and call that compliant
Don't expect the compensation for cancelled shifts to be generous. Early guidance points to a percentage of what you'd have earned, not the full shift value, and payroll systems at several large employers are still catching up - it's worth checking your own payslip line by line after a cancelled shift rather than assuming the payment has been added automatically, since manual HR claims are still common while systems get updated.
Who's still exempt or effectively unprotected
Genuinely casual arrangements - someone covering the odd shift with no expectation of regularity, students picking up occasional hospitality work around exams - sit outside the guaranteed-hours mechanism because there's no qualifying pattern to measure. Agency workers occupy a genuinely unresolved position: the Act extends some protections to agency staff, but the practical mechanics of calculating a "regular pattern" across an agency worker who's placed with three different clients in a quarter are still being worked out sector by sector, and agency contracts in the meantime often carry clauses that make the calculation deliberately hard to pin down.
There's also a harder truth worth naming: some employers are responding not by guaranteeing hours but by keeping shifts genuinely irregular on purpose, rotating workers just enough that no single pattern holds long enough to trigger the reference-period calculation. It isn't illegal on its face, and rota-management software aimed at hospitality and retail has started advertising "flexible scheduling" features that, read carefully, describe exactly this kind of rotation - a system built to stay one step ahead of a threshold.
What to actually do if your hours have been stable
Keep your own record of hours worked week by week, ideally with screenshots of the rota rather than relying on the employer's system, because the reference-period calculation depends on evidence you may need to produce yourself if a dispute arises. ACAS guidance recommends employees request a written statement of the hours the employer believes they've worked, which creates a paper trail and forces the employer to either confirm your own figures or explain a discrepancy - most simply confirm, because disputing your own timesheet against you is more work than it's worth for a shift supervisor.
If your employer offers a contract with fewer hours than you've actually been working, don't sign it as a formality. Ask, in writing, for the calculation behind the number - which weeks were included in the reference period, and whether any unusually quiet weeks were counted the same as busy ones. Getting this in writing matters more than getting an apology in person, because a verbal explanation from a manager carries no weight if the case ends up in front of an employment tribunal eighteen months later.
How this interacts with probation and the six-month rule
Guaranteed hours don't operate in isolation from the other headline change this year - the shift toward day-one unfair dismissal protection, tempered by a statutory probation window most commentators expect to land around six months. The two provisions were designed together, but employers have started using them in combination in ways the drafters probably didn't intend: extending a new hire's probation to the maximum permitted length specifically so any hours-averaging calculation runs out before the guaranteed-hours right would otherwise kick in. It's a legal use of two separate rules, and it's already being flagged by employment solicitors as the most likely area for early tribunal test cases once enough claims accumulate.
Retail in particular has leaned into this. A worker hired in March on a zero-hours contract, kept on an extended probation through August, and only assessed for guaranteed hours in September effectively loses six months of qualifying pattern compared to someone hired on a standard contract from day one. Whether that gap survives legal challenge is genuinely unresolved - the Act's guidance doesn't explicitly address probation-extension-as-avoidance, and unions have said publicly they expect this to be one of the first gaps closed by amendment rather than by tribunal precedent, since amendments move faster than case law once a pattern like this is identified.
Holiday pay and pension contributions move with it
Guaranteed hours don't just change the number on your contract - they change two calculations most workers never think to check. Holiday pay for irregular-hours staff is still commonly worked out using the 12.07% accrual method (52 weeks minus 5.6 weeks of statutory leave, expressed as a percentage of hours worked), and that percentage is applied to whatever hours figure sits in your contract. Move from a nominal "zero hours" line to a guaranteed 22 hours a week, and your holiday accrual recalculates against the higher number too - it isn't a separate negotiation, it follows automatically from the hours change, though payroll teams don't always flag that it's happened.
Pension auto-enrolment works off a similar logic. Contributions are calculated against qualifying earnings, and a worker whose averaged hours were too low or too irregular to trigger auto-enrolment thresholds in a given pay period can cross into eligibility once guaranteed hours smooth out the pattern. It's worth checking a payslip from three months after a guaranteed-hours contract starts against one from before it, because a jump in the pension deduction line is usually the guaranteed-hours change working as intended, not a payroll error - though it's still worth asking HR to confirm rather than assuming.
What this means if you're currently job hunting
Ask about the reference period during the interview, not after you've accepted the offer. A contract advertised as "zero hours, flexible" in a job listing might convert to guaranteed hours within a few months if the role turns out to be genuinely regular in practice - but you won't know that from the listing itself, and recruiters aren't always briefed on how their own client's rota patterns will play out against the new rules. Direct questions here aren't awkward; they're exactly the kind of due diligence that Citizens Advice and the CIPD are now actively recommending candidates raise before signing.
Sectors with historically heavy zero-hours use - hospitality, retail, home care, warehousing - are the ones where this actually changes take-home pay and predictability for real people, not just the legal paperwork sitting in a drawer. A care worker with a genuinely regular client list stands to gain a formal contract that a bank can actually use for a mortgage application, which is a change with consequences well beyond the workplace itself.