Zero-Hours Contracts and the Proof of Hours Worked

The message lands at half nine on a Tuesday night, phone lit up on the kitchen counter while the kettle is still going: cover needed for the six a.m. delivery slot, can you do it. There is no rota pinned to a noticeboard for this line of work, no fixed nine to five printed on a contract and filed away somewhere. The shift exists the moment someone agrees to it, and it stops existing the moment it is over. Reply yes and the day is already a little different from the one that was planned: an earlier start, a later finish, maybe a second call at four to see if anyone can stay a bit longer on the loading bay because a delivery ran late.

Warehouses run on this rhythm at peak, and so do event security teams filling a stadium gate for one Saturday, hotel banqueting staff called in for a wedding season nobody could plan a year out, home care visits added at short notice when a client’s regular carer is off sick, cleaning cover for an office that only needs extra hands after a big move. Zero-hours contracts exist precisely because demand does not arrive on a schedule, and for a business trying to cover it without carrying a full-time wage bill through the quiet weeks, the arrangement makes sense on paper. For the person taking the call, it can work too, provided the maths at the end holds up.

It usually does, right up until it does not. GOV.UK is blunt about what a zero-hours contract actually is: the employer does not have to give the worker any hours, and the worker does not have to accept work when it is offered. Neither side owes the other a fixed pattern, and since 2015 an employer cannot lock a zero-hours worker into exclusivity either, any clause trying to stop someone picking up a second job elsewhere is unenforceable, a rule Acas spells out on its own zero-hours guidance. What both sides do owe each other, contract or no contract, is the same as everyone else gets: the National Minimum Wage, statutory paid annual leave, treated no differently for being flexible rather than fixed.

Same rights, no fixed number to check them against

That equality on paper is where the trouble tends to start, because “the same rights as regular workers” assumes there is something fixed to measure them against. A worker on a set thirty-seven and a half hour week can spot an underpayment just by glancing at the rota. A zero-hours worker’s rota, such as it is, lives in a thread of text messages, a shift agreed over the phone, a favour picked up because someone is short-staffed on a Friday. Minimum wage compliance, holiday accrual, even the weekly rest the Working Time Regulations 1998 still apply to in full, all of it depends on knowing precisely which hours were actually worked. Not offered, not pencilled in: worked. Clocked on, clocked off, on that site, on that day. Without a fixed pattern to fall back on, every single shift has to prove itself from scratch.

Westminster has clocked the same gap. Over a million people in the UK work under zero-hours arrangements, and the Employment Rights Act 2025 is being phased in specifically to stop that flexibility running only one way, giving qualifying workers a right to a contract that reflects the hours they actually work, plus compensation when a shift is cancelled or cut short at the last minute. Read that carefully and it does not remove the need to prove hours worked, it depends on it. A right to a contract that reflects hours worked can only be calculated from hours that were actually recorded, shift by shift, over the reference period the law will look at. The reform raises the stakes on the record rather than making it optional.

Where memory turns into a dispute

It rarely breaks on a quiet week. It breaks at the end of the month, when the payslip lands and the Saturday looks two hours short of what the worker is certain they did, the two hours spent finishing a strip-out after the site manager asked for “just a bit longer.” The phone gets scrolled back through looking for proof, and what it turns up is a message asking someone to come in, not a record of when they actually left. The business, meanwhile, is reconstructing the same Saturday from a supervisor’s memory and whatever the client’s own sign-in sheet happened to catch, which for a contractor moving between sites is often nothing at all. Neither side is lying. Both are working from recollection, and recollection is exactly the thing a wage dispute, a client audit or a minimum wage inspection does not accept as evidence.

Proven hours matter to all three parties standing around that argument. For the worker, it is the difference between an estimate and a payslip that matches what was actually done, hour for hour, with holiday and any future guaranteed-hours calculation resting on the real total rather than a number rounded down out of habit. For the business, it is the record that closes the argument in one line instead of a week of back and forth, the same record a client, an auditor or an inspector will accept without asking a second question. For whoever commissioned the work in the first place, security cover at a one-off event, a cleaning contract spread across three sites, it answers a question that otherwise has no answer at all: who was actually there, and for how long.

The fix has nothing to do with bolting a rota onto a job that structurally cannot carry one. It is simpler than that: every call that turns into a shift needs a timestamp nobody can go back and rewrite, tied to where the person actually was when they clocked on and off, exportable by person and by site so a disputed Saturday can be reconstructed in seconds instead of a scrolled-through thread of messages. That is more or less the job GeoTapp does: a geo-timestamped clock-in for each shift, however irregular the call that triggered it, turning a contract that is variable by design into a record that is not.

Next time a shift starts with a message the night before, the question worth sitting with is not whether the call was fair. It is whether anyone, a month later, could actually prove when it started and when it ended. Anyone who would rather not find out the hard way can try GeoTapp’s free trial before the next call comes in.