42 CFR § 435.960 - Standardized formats for furnishing and obtaining information to verifying income and eligibility.
(a) The agency must maintain for all applicants and beneficiaries within an agency file the SSN, surname and other data elements in a format that at a minimum allows the agency to furnish and to obtain eligibility and income information from the agencies or programs referenced in § 435.945(b) and § 435.948(a).
(b) The format to be used will be prescribed by -
(1) CMS when the agency furnishes information to, or requests information from, any Federal or State agency, except SSA and the Internal Revenue Service as specified in paragraphs (b) (2) and (3), respectively;
(3) The Commissioner of Internal Revenue when the agency requests information from the Internal Revenue Service.