23 C.F.R. § 1200.34 – Program income.

(a) Definition. Program income means gross income received by the grantee or subgrantee directly generated by a program supported activity, or earned only as a result of the grant agreement during the period of time between the effective date of the grant award and the expiration date of the grant award.
(b) Inclusions. Program income includes income from fees for services performed, from the use or rental of real or personal property acquired with grant funds, from the sale of commodities or items fabricated under the grant agreement, and from payments of principal and interest on loans made with grant funds.
(c) Exclusions. Program income does not include interest on grant funds, rebates, credits, discounts, refunds, taxes, special assessments, levies, fines, proceeds from the sale of real property or equipment, income from royalties and license fees for copyrighted material, patents, and inventions, or interest on any of these.
(d) Use of program income.
1. (1) Addition. Program income shall ordinarily be added to the funds committed to the Highway Safety Plan. Such program income shall be used to further the objectives of the program area under which it was generated.
2. (2) Cost sharing or matching. Program income may be used to meet cost sharing or matching requirements only upon written approval of the Approving Official. Such use shall not increase the commitment of Federal funds.