45 CFR §2105.19

1. (a)When the Agency informs you of its decision to comply with a request by granting, partially granting, or denying the request, it will do so in writing and in accordance with the deadlines in subpart D of this part. The Agency's written response will include a statement about the services offered by its FOIA Public Liaison. The Agency's written response will also include a statement about the services offered by the Office of Government Information Services (OGIS).
2. (b)If the Agency determines that your request will take longer than 10 workdays to process, the Agency immediately will send you a written acknowledgment that includes the request's individualized tracking number and processing track (see § 2105.14(e)). The acknowledgement may also include a brief description of the subject of your request.