The Office of Audit Services (OAS) conducts independent audits of HHS programs and/or HHS grantees and contractors. These audits examine the performance of HHS programs and/or grantees in carrying out their responsibilities and provide independent assessments of HHS programs and operations. These assessments help reduce waste, abuse, and mismanagement and promote economy and efficiency throughout HHS. OAS conducts audits using its own resources and oversees audit work performed by others. OAS is the largest civilian audit agency in the Federal Government. OAS conducts its work in accordance with Government Auditing Standards issued by the Comptroller General of the United States; the Single Audit Act Amendments of 1996; applicable Office of Management and Budget circulars; and other legal, regulatory, and administrative requirements.
Further reading –
https://oig.hhs.gov/about-oig/about-us/office-of-audit-services.asp