I’ve been seeing so much RiF talk/assumptions; always fact check...
Federal statute requires agencies to take reduction-in-force (RiF) action against employees who have been furloughed for 30 days or more, but that only applies in administrative furloughs. Furloughs of federal workers as a result of lapses in appropriation are called emergency furloughs.
According to the U.S. Office of Personnel Management, reduction-in-force regulations dont apply in such events:
Reductions in force (RIF) furlough regulations and SES competitive furlough requirements are not applicable to emergency shutdown furloughs because the ultimate duration of an emergency shutdown furlough is unknown at the outset and is dependent entirely on Congressional action, rather than agency action. The RIF furlough regulations and SES competitive furlough requirements, on the other hand, contemplate planned, foreseeable, money-saving furloughs that, at the outset, are planned to exceed 30 days.
Actually it is a lot more complex than that. I can provide link to more info later on.