A joint audit is an audit on a legal entity (the auditee) by two or more auditors to produce a single audit report, thereby sharing responsibility for the audit. A typical joint audit has audit planning performed jointly and fieldwork allocated to the auditors. The auditors are typically not individuals, but auditing firms. This work allocation may be rotated after a set number of years to mitigate the risk of over-familiarity. Work performed by each auditor is reviewed by the other, in most cases by exchanging audit summary reports. The critical issues at group level, including group consolidation, are reviewed jointly and there is joint reporting to the legal entity's management, its audit committee, a government entity, or the general public.

A joint audit is different from a dual audit, where a dual audit is performed by two independent auditors issuing their own separate reports, which are then used by another auditor that ultimately reports on the entity as a whole. Since the audit reform in 2014 in Europe, joint auditing is encouraged but not obligated by the law. In combination with mandatory rotation it's effective to diversify the audit market. In France the joint audit system is obligated by law for PIE's.