25 C.F.R. § 1000.1235
How does the Secretary respond to a waiver request?
Within 10 business days of receipt, the officials designated by the Secretary in § 1000.1215 will email to the Tribe/Consortium a letter:
(a) Acknowledging receipt of the waiver request; and
(b) Identifying the date the waiver request was received and the last day of the applicable statutory review period.