29 C.F.R. § 2570.38

(a) If, after reviewing an exemption file, the Department tentatively concludes that it will not propose or grant the exemption, it will notify the applicant in writing. At the same time the Department provides the notification, the Department will also provide a brief statement of the reasons for its tentative denial.

(b) An applicant will have 20 days from the date of a tentative denial letter, unless the Department extends the time period at its sole discretion, to request a conference under § 2570.40 and/or to notify the Department of its intent to submit additional information under § 2570.39. If the Department does not receive a request for a conference or a notification of intent to submit additional information within that time, it will issue a final denial letter pursuant to § 2570.41.