2 CFR § 180.760 - How long may my suspension last?
(a) If legal or debarment proceedings are initiated at the time of, or during your suspension, the suspension may continue until the conclusion of those proceedings. However, if proceedings are not initiated, a suspension may not exceed 12 months.
(b) The suspending official may extend the 12 month limit under paragraph (a) of this section for an additional 6 months if an office of a U.S. Assistant Attorney General, U.S. Attorney, or other responsible prosecuting official requests an extension in writing. In no event may a suspension exceed 18 months without initiating proceedings under paragraph (a) of this section.
(c) The suspending official must notify the appropriate officials under paragraph (b) of this section of an impending termination of a suspension at least 30 days before the 12 month period expires to allow the officials an opportunity to request an extension.