23 CFR § 710.505 - Real property donations.
(a) Donations of property being acquired. A non-governmental owner whose real property is required for a title 23 project may donate the property. Donations may be made at any time during the development of a project subject to applicable State laws. Prior to accepting the property, the owner must be informed in writing by the acquiring agency of his/her right to receive just compensation for the property, the right to an appraisal or waiver valuation of the real property, and of all other applicable financial and non-financial assistance provided under 49 CFR part 24 and applicable State law. All donations of property received prior to the approval of the NEPA document for the project must meet the requirements specified in 23 U.S.C. 323(d).
(b) Credit for donations. Donations of real property may be credited to the State's matching share of the project in accordance with 23 U.S.C. 323. As required by 23 U.S.C. 323(b)(2), credit to the State's matching share for donated property shall be based on fair market value established on the earlier of the following: Either the date on which the donation becomes effective, or the date on which equitable title to the property vests in the State. The fair market value shall not include increases or decreases in value caused by the project. The grantee shall ensure sufficient documentation is developed to indicate compliance with paragraph (a) of this section and with the provisions of 23 U.S.C. 323, and to support the amount of credit applied. The total credit cannot exceed the State's pro-rata share under the project agreement to which it is applied.
(c) Donations and conveyances in exchange for construction features or services. A property owner may donate property in exchange for construction features or services. The value of the donation is limited to the fair market value of property donated less the cost of the construction features or services. If the value of the donated property exceeds the cost of the construction features or services, the difference may be eligible for a credit to the State's share of project costs.