5 C.F.R. § 2424.21
(a) A petition for review must be filed within fifteen (15) days after the date of service of either:
(b) If the agency has not served a written allegation on the exclusive representative within ten (10) days after the agency's principal bargaining representative has received a written request for such allegation, as provided in § 2424.11(a), then the petition may be filed at any time, subject to the following:
[88 FR 62456, Sept. 12, 2023]