I currently work at an employer that doesn't allow rolling/carrying over any vacation time from year to year. I understand the need to not allow too much carryover - otherwise you end up with people with months' worth of vacation pay, that you might have to pay out (depending on state laws) if their employment is terminated. But a policy to allow a few days to roll over doesn't have that problem. Is it just an accounting problem - more paperwork for them (the HR department)?