; (2) licensees or registrants of an earth station receiving signals over the spectrum identified under section 3(a)(1); and (3) the relocation of other incumbent uses of the spectrum identified under section 3(a)(1). (e) Implementation The Commission shall use not more than $1,000,000,000 of the amounts in the C-Band Fund for payments to incentivize incumbent holders of licenses or market access rights for use of the electromagnetic spectrum identified under paragraph (1) of section 3(a) to reduce their usage of that spectrum in accordance with that section in a more timely fashion. (f) Transfer of unused funds If any amounts remain in the C-Band Fund after the date that is 3 years after the completion of the system of competitive bidding conducted under section 3, the Secretary of the Treasury shall transfer those amounts to the Digital Divide Trust Fund. 6. Spectrum auction participation (a) In general Section 309(j) of the Communications Act of 1934 ( 47 U.S.C. 309(j) ) is amended— (1) in paragraph (17)(A), in the matter preceding clause (i), by striking Notwithstanding and inserting Subject to paragraph (19) and notwithstanding ; and (2) by adding at the end the following: (19) Prohibition on auction participation by entities posing a national security risk (A) In general An entity posing a national security risk may not participate in any system of competitive bidding under this subsection. (B) Definition (i) In general For purposes of this paragraph, the term entity posing a national security risk means an entity that the Commission determines poses a national security risk. (ii) Determination In determining which entities qualify as entities posing a national security risk under this paragraph, the Commission shall rely solely upon a determination by— (I) an appropriate national security agency; (II) an interagency body that includes appropriate national security expertise, including the Federal Acquisition Security Council established under section 1322 of title 41, United States Code; (III) Congress