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HMRC internal manual

Employment Status Manual

Agency and temporary workers: overarching contracts of employment - zero hours contract

A zero hour contract generally is a contract where the employer does not guarantee to provide the worker with work and will only pay the worker for those hours which are actually worked.

Whilst a zero hour contract does not include a minimum hours work guarantee, it may contain examples of other obligations on the part of the employer - for example, it may contain a provision to pay a retainer.

You should not conclude that a contract cannot be an overarching contract of employment purely on the basis that it is a zero hour contract which does not provide a guaranteed minimum number of hours. You should fully establish what, if any, mutual obligations exist in the contractual arrangements.