25 C.F.R. § 62.6 – Filing of an appeal.

(a) Except as provided in paragraph (b) of this section, a notification of an adverse enrollment action will be mailed to the address of record or the last available address and will be considered to have been made and computation of the appeal period shall begin on:
1. (1) The date of delivery indicated on the return receipt when notice of the adverse enrollment action has been sent by certified mail, return receipt requested; or
2. (2) Ten (10) days after the date of the decision letter to the individual when notice of the adverse enrollment action has not been sent by certified mail return receipt requested and the letter has not been returned by the post office; or
3. (3) The date the letter is returned by the post office as undelivered whether the notice of the adverse enrollment action has been sent by certified mail return receipt requested or by regular mail.
(b) When notification of an adverse enrollment action is under the regulations contained in part 61 of this chapter, computation of the appeal period shall be in accordance with § 61.11.
(c) In computing the 30 or 60 day appeal period, the count begins with the day following the notification of an adverse enrollment action and continues for 30 or 60 calendar days. If the 30th or 60th day falls on a Saturday, Sunday, legal holiday, or other nonbusiness day, the appeal period will end on the first working day thereafter.