Appointment of Cost Auditor requires certificate of compliance with audit-number limits and prior central government approval. Appointment of a Cost Auditor requires prior Central Government approval and a written certificate that the appointment will comply with sub-section (1B) of Section 224; for that certificate the auditor must count only companies for which he holds firm written letters of appointment. A Cost Auditor's term is deemed to have concluded once he submits the cost audit report to the Central Government with a copy to the company, and his obligation to answer review queries does not bar accepting a new appointment so long as the audit-number limit is not exceeded.