The Family Medical Leave Act (FMLA) gives many employees the right to take up to 12 weeks of unpaid leave without worrying that their jobs will vanish while they’re gone. It’s designed to make it easier for workers to balance their medical and family needs while remaining employed. But many Americans aren’t actually aware of how the FMLA actually works.

Here are three things you should know about the FMLA:

  1. Are all employers required to adhere to the FMLA’s guidelines?

No. All government agencies and schools must comply with the FMLA, but private employers must generally have 50 or more employees to fall under its guidelines.

  1. Are all employees of covered employers entitled to leave under the FMLA?

No. Even though your employer is subject to the FMLA, you may still not be eligible for leave. Eligible employees must generally:

  • Have worked for an employer for 12 months (although they do not have to be consecutive)
  • Have worked for your employer at least 1,250 hours (approximately 24 hours per week if you work each week of the year) during the last 12 months
  • Work at a location where the employer has at least 50 employees within a 75-mile radius (which means you’re ineligible, for example, if you work in a small satellite office in the middle of nowhere hundreds of miles away from the main corporation)
  1. Can you take FMLA for any family member?

No. Generally speaking, you can only take advantage of the FMLA when it’s your own condition that requires the leave or the condition of an immediate family member, such as a parent, a spouse, a minor child, an adult child who is incapable of self-care due to their mental or physical limitations or a child for whom you are standing “in loco parentis” for some reason (such as a grandchild over whom you have custody).

Even with these limitations, the FMLA is a godsend to many workers and their families every year — but only when they’re permitted to exercise their rights. Despite the law, some employers won’t be happy about an employee’s use of the FMLA, and they may retaliate or try to make the process as difficult as possible. If that happens, find out more about your legal options.