Setting Limits on Pay Outs of Accrued Vacation Time

Background: On Jan 1, 2023 we instituted several changes to employee time off accrual policies. We constructed the new vacation accrual policies carefully and gave some of our more senior staff "legacy policies" in order to not decrease any current employee's vacation accrual rate. However, we DID institute a cap on the number of vacation hours an employee could bank at any given time (1/2 a year for FT staff, and 1/4 yr FTE for PT staff). We did this for two reasons: 1) to mitigate financial risk to our library in the event of unforeseen separations, when we pay out any unused vacation time, and 2) to encourage staff to take regular vacations, which prevents burnout and encourages us to understand each other's job responsibilities better when covering for someone else.

Unfortunately, the vacation cap has had some unintended consequences. Some staff members are reticent to take vacation and are bumping up against the cap each month, which effectively means their compensation is being reduced. Also, our PT staff work varying number of hours per week (20-32) but we don't prorate the PT vacation cap (for logistical reasons), which makes it difficult for staff who work close to FT hours to save up enough time to take a longer vacation, or multiple vacations in a relatively short period.

My legal question is: If we were to change our time off accrual policy to allow staff to bank as much vacation as they like but specify that upon separation they could only be paid out 'x' number of hours, could we be accused of wage theft?