A zero-hours contract (“nulurencontract”) can feel like a simple lever: pull it when the work is there, release it when it isn’t. But the legal reality is less elastic. The moment flexibility starts creating unpredictable income for the worker or unpredictable obligations for you the rules tighten. And when they tighten, the first place you feel it is not in courtrooms, but in cash flow: unexpected wage costs after a cancelled shift, admin time spent answering formal requests, and awkward conversations when a “temporary” arrangement quietly turns into a fixed-hours expectation.
Start with the blunt rule many small businesses miss: a zero-hours contract cannot simply run on forever. In principle, you cannot keep someone on a zero-hour contract longer than 26 weeks. There can be exceptions, but only when your sector’s collective labour agreement (“cao”) explicitly allows it and the work is genuinely incidental, think peak periods or sickness cover, not a permanent role disguised as “call when needed.” If your weekly planning looks busy most weeks, it’s hard to argue the hours have “no fixed scope,” and that is exactly where the risk shows up.
Then there’s the one-year turning point, which hits right at the moment many micro-employers finally feel they can rely on someone. After 12 months, you must offer a contract for the average number of hours the person worked in that year. If the employee accepts, it stops being a zero-hours situation, full stop. Only if they refuse and explicitly prefer to remain on an on-call basis (“oproepcontract”) can you continue that way. Practically, this means your own rostering history becomes evidence. If you’ve been calling someone almost every week, the “average hours” offer can be larger than you expected, and once accepted it becomes a stable monthly cost.
The timing rules are another quiet expense. Under the Wet arbeidsmarkt in balans (“WAB,” in force since 1 January 2020), your on-call worker only has to come in if you call them at least four days in advance. Cancel within four days, and you still have to pay the hours you cancelled. Many owners learn this the hard way: a client postpones a delivery, you cancel a shift, and you discover you’ve just bought an empty day. That is not “red tape”; it’s a direct hit to margin. The fix is not panic, it’s planning discipline and clearer client agreements so your own schedule stops changing at the last minute.
Layered on top is the EU-driven push for “predictable working conditions” (since August 2022). In plain terms: if someone’s working times are unpredictable, you must create a predictable pattern. That means putting reference days and reference hours into the contract, specific windows when the person can be called. After six months, the worker can also make a written request for more certainty (for example, more fixed hours), and you must respond seriously; if you refuse, you need a solid reason. This is where admin load grows: the law expects you to document your choices, not just make them.
Finally, keep an eye on sector rules. The government can restrict zero-hours contracts in specific sectors, through the Ministry of Social Affairs and Employment (“SZW”), potentially at the request of the Stichting van de Arbeid (a key labour advisory body). Some sectors, like parts of healthcare, already try to minimise nulurencontracten through their cao, even without a full ban. And while proposals about broader changes for 2027 exist, approval and start dates are not guaranteed. For a small business, the point is simpler: don’t run your staffing model on rumours, run it on today’s enforceable rules and your actual cao text.
The calm way forward is not to “avoid flexibility,” but to design it so it doesn’t surprise you later. Keep your contracts aligned with how the work truly behaves; if you need someone most weeks, treat that as a role with a baseline. Call people in time, cancel less, and tighten client commitments so your planning isn’t constantly rewritten. And if you do rely on on-call staff, make the predictability explicit, clear calling windows, clear records, clear offers after a year. In a small company, trust is currency. The simplest compliance habits are often the cheapest form of insurance.
