https://www.employment.govt.nz/hours-and-wages/hours-of-work/ の cancellation of shifts によると、以下のようになっています。

シフトのキャンセルに関する規定が雇用契約書に規定されていたら、給与保証はそれによります。この場合、シフトキャンセルの通知がシフトの始まるどれほど前に与えられたかによって給与保証の有無は変わってきます。
"If an employee is a shift worker, their employer can’t cancel one or more of their shifts unless:

the employment agreement has:
a reasonable period of notice for cancellation, and
reasonable compensation payable to the employee if the employer cancels a shift without giving reasonable notice, and
the employer either gives the employee the above notice or pays the reasonable compensation above, and
cancelling the shift doesn’t breach the employment agreement."


規定されていない場合は、シフトに入っている時間分の給与が支払われなければなりません。
"If the employment agreement doesn’t have a valid shift cancellation provision (with reasonable notice period and reasonable compensation for shift cancellation) and the employer cancels a shift anyway, then, because they can’t do this, the employer must pay the employee what they would have been paid if they had worked the shift. "