Employment Relations Act 2000, ss 67D-67F
Workers have some legal protections against arrangements like “zero-hour” contracts – that’s where you have no guaranteed hours of work but must be available for whatever hours your employer offers, whenever they offer them.
Your employment agreement can include a clause giving your employer some freedom about whether they make work available to you and requiring you to accept the work, but only if:
your agreement gives you some guaranteed hours
you’re paid reasonable compensation (see below) for making yourself available above those guaranteed hours, and
your employer has genuine reasons based on reasonable grounds for including this kind of availability clause.
If there’s not an availability clause in your agreement that meets those requirements, you’re free to turn down any work you’re offered above your guaranteed hours. If you do turn the work down, your employer can’t fire you or disadvantage you in any way.
Employment Relations Act 2000, ss 65(4), 67C
Note: If you and your boss have verbally agreed about what your hours will be, your boss must make sure this is stated in your written employment agreement. This includes where you’ve agreed on a number of guaranteed hours, or on the days of the week you’ll work, or on start and finish times, or on any flexibility about those issues. If your boss doesn’t include this in your written agreement, you (or a labour inspector) can take them to the Employment Relations Authority, who can then order them to pay a monetary penalty.