In 2007 we implemented a change in our policy from a "carry over with a cap" to a "use it or lose it policy" (25% of the annual accrual still allowed to carry). It was met with great resistance because employees were counting on big vacation payouts should the day come when they separate employment, as they had seen others get. Post separation payouts are limited by the new policy to 80 hours.
Managers were also frustrated because now they needed to accomodate their employees actually taking their alloted vacation time and the large balances they were carrying to get down to the allowable carry over, which is 25% of the annual accrual. For the first year only, the "transition year", we allowed employees who couldn't manage to use all of their time, to put the balance into a bank to be used only to offset future disability payments, should they ever need to use that. This feature was strictly voluntary. We had been advised by legal to put this provision in for the transition year.
Since employees accrue on a per payperiod basis, the new policy allows them to "go negative" , no more than 40 hours, to accomodate time they might want to take early in the year, but have not yet earned. They sign an acknowledgement, approved the by the DOL, that any negative balance will be paid back to the employer at the time of separation through payroll deduction.
We have seen the benefits now two years later, following 2 reductions in force, and less dollars spent on vacation payouts. Employees are using their time off, which results in a more rested and balanced workforce. There is still some grumbling at not being able to "hoard" time as addition potential severence benefits down the line, but for the most part, everyone has adjusted.