The Federal Office of Management and Budget (OMB) issues directives that apply to all federal agencies about administration, cost principles and accounting, and auditing requirements. These directives also apply to the grantees and subgrantees of federal agencies, including state units on aging, area agencies on aging, and subgranted senior service providers.
Here is page that links each OMB Circular http://www.whitehouse.gov/omb/circulars_default