5 C.F.R. § 294.110 – Appeals.

(a) When an OPM official denies records or a waiver of fees under the Freedom of Information Act, the requester may appeal to the—
Office of the General Counsel, Office of Personnel Management, Washington, DC 20415
(b) A person may appeal denial of a Freedom of Information Act request for information maintained by OPM's Office of the General Counsel to the—
Deputy Director, Office of Personnel Management Washington, DC 20415
(c) If an official of another agency denies a Freedom of Information Act request for records in one of OPM's Government-wide systems of records, the requester should consult that agency's regulations for any appeal rights that may apply. An agency may, at its discretion, direct these appeals to OPM's Office of the General Counsel.
(d) An appeal should include a copy of the initial request, a copy of the letter denying the request, and a statement explaining why the appellant believes the denying official erred.
(e) The appeals provided for in this section constitute the final levels of administrative review that are available. If a denial of information or a denial of a fee waiver is affirmed, the requester may seek judicial review in the district court of the United States in the district in which he or she resides, or has his or her principal place of business, or in which the agency records are situated, or in the District of Columbia.