43 C.F.R. § 2.59
How do you file an appeal?
(a) You must submit the appeal in writing by mail, fax or email to the FOIA Appeals Officer (using the address available at http://www.doi.gov/foia/appeals). Your failure to send an appeal directly to the FOIA Appeals Officer may delay processing.
(b) The appeal must include:
(1) Copies of all correspondence between you and the bureau concerning the FOIA request, including the request and the bureau's response (if there is one); and
(2) An explanation of why you believe the bureau's response was in error.
(c) The appeal should include your name, mailing address, daytime telephone number (or the name and telephone number of an appropriate contact), email address, and fax number (if available) in case the Department needs additional information or clarification.
(d) An appeal concerning a denial of expedited processing or a fee waiver denial should also demonstrate fully how the criteria in § 2.20 or §§ 2.45 and 2.48 of this part are met.
(e) All communications concerning an appeal should be clearly marked with the words: “FREEDOM OF INFORMATION APPEAL.”
(f) The Department will reject an appeal that does not attach all correspondence required by paragraph (b)(1) of this section, unless the FOIA Appeals Officer determines, in his or her sole discretion, that good cause exists to accept the defective appeal. The time limits for responding to an appeal will not begin to run until the correspondence is received.