28 CFR 16.6: Responses to requests.
On receipt of a request, a component ordinarily shall send an acknowledgement letter to the requester which shall confirm the requester's agreement to pay fees under § 16.3(c) and provide an assigned request number for further reference.
Ordinarily, a component shall have twenty business days from when a request is received to determine whether to grant or deny the request. Once a component makes a determination to grant a request in whole or in part, it shall notify the requester in writing. The component shall inform the requester in the notice of any fee charged under § 16.11 and shall disclose records to the requester promptly on payment of any applicable fee. Records disclosed in part shall be marked or annotated to show the amount of information deleted unless doing so would harm an interest protected by an applicable exemption. The location of the information deleted also shall be indicated on the record, if technically feasible.
A component making an adverse determination denying a request in any respect shall notify the requester of that determination in writing. Adverse determinations, or denials of requests, consist of: a determination to withhold any requested record in whole or in part; a determination that a requested record does not exist or cannot be located; a determination that a record is not readily reproducible in the form or format sought by the requester; a determination that what has been requested is not a record subject to the FOIA; a determination on any disputed fee matter, including a denial of a request for a fee waiver; and a denial of a request for expedited treatment. The denial letter shall be signed by the head of the component, or the component head's designee, and shall include:
(1) The name and title or position of the person responsible for the denial;
(2) A brief statement of the reason(s) for the denial, including any FOIA exemption applied by the component in denying the request;
(3) An estimate of the volume of records or information withheld, in number of pages or in some other reasonable form of estimation. This estimate does not need to be provided if the volume is otherwise indicated through deletions on records disclosed in part, or if providing an estimate would harm an interest protected by an applicable exemption; and
(4) A statement that the denial may be appealed under § 16.9(a) and a description of the requirements of § 16.9(a).