(a) By eligible entities. A transferee or lessee may permit the use of all or a portion of the surplus Federal real property by another eligible entity as described in § 12.5, only upon those terms and conditions the Secretary determines appropriate if—

(1) The Secretary determines that the proposed use would not substantially limit the program and plan of use by the transferee or lessee and that the use will not unduly burden the Department;

(2) The Secretary's written consent is obtained by the transferee or lessee in advance; and

(3) The Secretary approves the use instrument in advance and in writing.

(b) By ineligible entities. A transferee or lessee may permit the use of a portion of the surplus Federal real property by an ineligible entity, one not described in § 12.5, only upon those terms and conditions the Secretary determines appropriate if—

(1) In accordance with paragraph (a) of this section, the Secretary makes the required determination and approves both the use and the use instrument;

(2) The use is confined to a portion of the surplus Federal real property;

(3) The use does not interfere with the approved program and plan of use for which the surplus Federal real property was conveyed; and

(4) Any rental fees or other compensation for use are either remitted directly to the Secretary or are applied to purposes expressly approved in writing in advance by the Secretary.