The Audit Office is an autonomous unit that independently and without receiving instructions reviews the budgetary and financial management of the City of Mainz and reports its findings directly to the Mayor. The Audit Office reviews the annual and consolidated financial statements, as well as the regularity, appropriateness, and cost-effectiveness of the administration.

Other areas of responsibility include the Anti-Corruption Office and the reporting office established under the Whistleblower Protection Act, as well as the audit of information security.