Zero hours contracts — formally described as casual or on-call contracts — guarantee no minimum hours of work. The employer offers work when it is available; the worker decides whether to accept it. That is the theory. In practice, the power imbalance means many zero hours workers feel unable to decline shifts, creating an employment relationship that in substance resembles regular employment while offering few of its protections.
Understanding what the law actually requires — and what clauses in a zero hours contract should and should not contain — matters both for workers assessing their position and for employers who want to ensure their arrangements are legally sound.
Paste any clause for an instant plain-English risk assessment — including your rights, red flags, and what to push back on.
What rights do zero hours workers have?
The rights you hold under a zero hours contract depend on whether you are classified as an employee or a worker. Most zero hours arrangements create a worker relationship rather than full employment — but even workers have substantial statutory protections that many people on zero hours contracts do not realise they hold.
Workers on zero hours contracts are entitled to the National Minimum Wage for all hours worked, statutory annual leave of 5.6 weeks (calculated on a pro-rata basis based on hours worked), protection from unlawful discrimination, and the right not to be penalised for exercising statutory rights. Workers who have worked for 26 weeks or more may also be entitled to request a more stable and predictable contract under the Employment Relations (Flexible Working) Act 2023.
If your working pattern in practice resembles regular employment — if you work set hours each week, if you are expected to be available, if your shifts are regular rather than genuinely occasional — you may in fact be an employee with the full range of employment rights, regardless of what the contract says.
The exclusivity clause ban
One of the most significant legal developments for zero hours workers was the ban on exclusivity clauses introduced by the Small Business, Enterprise and Employment Act 2015. It is unlawful for an employer to include a clause in a zero hours contract requiring the worker to work exclusively for that employer.
An exclusivity clause in a zero hours contract — one that prevents you from working for anyone else — is void and unenforceable. Furthermore, it is unlawful for an employer to subject a zero hours worker to a detriment for working for another employer, or to terminate a zero hours arrangement because the worker has taken other work.
If your zero hours contract contains an exclusivity clause, that clause has no legal effect. You are free to work for other employers regardless of what it says.
Holiday pay on zero hours contracts
Zero hours workers accrue annual leave in proportion to the hours they work. The entitlement is 5.6 weeks per year, and for workers whose hours vary, holiday pay is calculated as an average of pay received over the preceding 52 weeks (ignoring weeks in which no work was done).
Holiday pay cannot lawfully be "rolled up" into an hourly rate — a practice where employers pay a slightly higher hourly rate and treat it as inclusive of holiday pay. The Supreme Court confirmed in Brazel v Harpur Trust [2022] that holiday pay must be paid at the time holiday is taken, and that the 12.07% calculation method commonly used for casual workers may understate the entitlement for those who work year-round.
Detriment for refusing work
You cannot be subjected to a detriment for refusing work offered under a zero hours contract. A detriment means any disadvantage — being offered fewer shifts in future, being moved to less desirable shifts, being treated less favourably in any way. If an employer effectively punishes workers for exercising their right to decline shifts, this may give rise to a tribunal claim.
In practice, this right is difficult to enforce because proving the causal link between a refusal and subsequent treatment is challenging. But the right exists, and a pattern of reduced offers following a refusal is capable of supporting a claim.
Clauses to watch for
Beyond the exclusivity ban, there are several clauses worth reviewing in any zero hours contract. A clause requiring you to be available at all times or to be on standby without pay raises questions about whether those standby hours should themselves be remunerated. A clause allowing the employer to vary your terms unilaterally — including your rate of pay — with short or no notice is significant in any contract.
Pay particular attention to any clause that attempts to characterise the relationship as self-employment rather than worker status. If you work regularly, under direction, using the employer's equipment, the label will not determine your rights — but it can complicate enforcement.
Requesting a fixed-hours contract
Workers who have been engaged for 26 weeks continuously have the right to request a more predictable and stable contract under legislation introduced in 2023. The employer must respond to such a request within one month and can only refuse on specified grounds.
This right does not guarantee that you will receive a fixed-hours contract — but it does create a formal process and protects you from detriment for making the request.
If you think you are being misclassified
If your zero hours arrangement in practice looks like regular employment — if you work a regular pattern, if you feel unable to refuse shifts, if the employer exercises significant control over how and when you work — you may have worker or employee status regardless of the contract. A claim for employment status can be brought in the employment tribunal.
Before bringing a claim, it is worth taking advice from ACAS (whose early conciliation service is free) or from a solicitor. The Employment Rights Act 1996 provides the framework for status claims, and the tribunal will look at the reality of the relationship rather than the contractual label.