5 C.F.R. § 9800.107
(a) Appeals of adverse determinations. A requester may appeal a determination denying a FOIA request in any respect to the CIGIE Chairperson c/o Office of General Counsel, Council of the Inspectors General on Integrity and Efficiency, 1717 H Street NW, Suite 825, Washington, DC 20006. The appeal must be in writing, and must be submitted either by:
(c) Adjudication of appeals.