Mutuality of Obligation (MOO)

Short Definition: An IR35 test that evaluates the obligations between a client and a contractor.

Long Definition: Mutuality of Obligation (MOO) refers to whether a client is obliged to provide work and the contractor is obliged to accept it. In genuine self-employment, work is task-based with no ongoing commitment. If MOO exists, it may indicate an employer-employee relationship, bringing the engagement inside IR35.