26 C.F.R. § 1.77-1
A taxpayer who receives a loan from the Commodity Credit Corporation may, at his election, include the amount of such loan in his gross income for the taxable year in which the loan is received. If a taxpayer makes such an election (or has made such an election under section 123 of the Internal Revenue Code of 1939 or under section 223(d) of the Revenue Act of 1939 (53 Stat. 897)), then for subsequent taxable years he shall include in his gross income all amounts received during those years as loans from the Commodity Credit Corporation, unless he secures the permission of the Commissioner to change to a different method of accounting. Application for permission to change such method of accounting and the basis upon which the return is made shall be filed with the Commission of Internal Revenue, Washington, D.C. 20224, within 90 days after the beginning of the taxable year to be covered by the return.
26 C.F.R. §1.77-1