45 CFR § 2105.49
What if the Agency needs clarification about fee issues?
April 14, 2021
If your FOIA request does not contain sufficient information for the Agency to determine your proper fee category or leaves another fee issue unclear, the Agency may ask you to provide additional clarification. If it does so, the Agency will notify you that it will not be able to comply with your FOIA request unless you provide the clarification requested.