Generally, employers can put reasonable restrictions on the use of vacation time to coincide with business needs, says employment law attorney Scott Leah of the firm Tucker Arensberg, P.C.

For example, if your company has a busy season and needs all hands on deck, you can restrict employees from taking vacation during that period of time. So if summers are slow, you could require employees to use vacation between April and September. However, you can’t make the restrictions so severe the time is almost impossible to use.

While PTO can certainly be crafted as subject to the needs of the business, it usually incorporates the old “vacation” and “sick” time; therefore, it includes some unplanned absences, which cannot be scheduled in advance, HR Consultant Ruth Bassham explains.

Blackout dates could prove difficult to regulate unless there are separate provisions for pre-scheduled and unscheduled absences, Bassham points out. Limiting the time allowed at once or in designated intervals is very specific to the environment, including business needs and the occurrence of policy abuse in the population.

It depends on the industry, says Haley Burrow, Manager, Talent Acquisitions. For example, in the retail industry, the day after Thanksgiving would likely be considered a “blackout date.” Every employee is needed on that day. In some companies, blackout dates are only needed if there is a major project or a new system implementation that will require an all-hands-on-deck approach.

First, the business model — e.g., retail vs. manufacturing — must be taken into consideration, according to HR Manager Alice Parker.

Since I work in manufacturing that is what I will comment on, she says. In my experience, we do not blackout any specific dates; instead, we allow managers to control their employees’ PTO schedules to ensure proper coverage. Our policy states that no more than three consecutive weeks of PTO can be taken.