OMB A-133 Compliance Supplement

The OMB A-133 Compliance Supplement is a large and extensive United States federal government guide created by the Office of Management and Budget (OMB) and used in auditing federal assistance and federal grant programs, as well as their respective recipients. It is considered to be the most important tool of an auditor for a Single Audit.
It was created following amendments in 1996 to the Single Audit Act based on numerous studies performed by the Government Accountability Office, the President's Council on Integrity and Efficiency and the National State Auditors Association (NSAA). It serves to identify existing important compliance requirements that the Federal Government expects to be considered as part of a Single Audit. Without it, auditors would need to research many laws and regulations for each single program of a recipient to determine which compliance requirements are important to the Federal Government. For Single Audits, the Supplement replaces any agency audit guides and other audit requirement documents for individual Federal programs.
Divisions.
The OMB A-133 Compliance Supplement is divided into 7 divisions:
Compliance requirements.
Compliance requirements are series of directives established by US federal government agencies that guide recipients and auditors on how federal assistance should be managed. The OMB created 14 basic requirements which group all those compliance requirements and provided extensive array of information about them in the Compliance Supplement.
Further reading.
OMB Circulars.
The following is a list of circular letters issued by the US Office of Management and Budget which provide significant information and guidance for Federal agencies, recipients, auditors, and the general public over the use and management of federal funds, operations of federal assistance programs, and agencies' and recipients' compliance requirements over laws and regulations imposed by the federal government: