gc@chimentowebb.com, there are of course proposed 457(f) regulations that are fairly clear and reasonable on this point, and that can be relied on until withdrawn or changed in the final. Given that it is a "facts and circumstances" determination, there is no bright line certainty, but my guess would be that what you describe is probably not outside the boundaries, assuming the amount of vacation per year is reasonable and designed to actually have employees take vacation, i.e. the employee could reasonably be expected to take it and would be unlikely to use it as a "piggy bank." I would probably be concerned if the frequency of "extra staffing needs" led to a situation where the 25% limit on cashouts was seldom applicable in practice. But again, it's facts and circumstances and I'm sure your brief description leaves out some of those. Here is the language from the proposed regulations on this point:
Factors used in determining whether a plan is a bona fide sick or vacation leave plan include whether the amount of leave provided could reasonably be expected to be used in the normal course by an employee (before the employee ceases to provide services to the eligible employer) absent unusual circumstances, the ability to exchange unused accumulated leave for cash or other benefits (including nontaxable benefits and the use of leave to postpone the date of termination of employment), the applicable restraints (if any) on the ability to accumulate unused leave and carry it forward to subsequent years in circumstances in which the accumulated leave may be exchanged for cash or other benefits, the amount and frequency of any in-service distributions of cash or other benefits offered in exchange for accumulated and unused leave, whether any payment of unused leave is made promptly upon severance from employment (or instead is paid over a period after severance from employment), and whether the program (or a particular feature of the program) is available only to a limited number of employees.