Yes there is, ask your manager about it. I think everyone gets the extra bonus of increased goals and Christmas off if you use one of your 21 PTO days.
Didn't the tell you that you have 21 vacation/PTO days? All vacation and holiday time is lumped in to one bucket so if you want to take any holiday off like Christmas, New Years Day, Thanksgiving , etc... you need to use one of your vacation days. There are no holiday's off.
Might as well work Christmas otherwise you have to take a vacation day. Besides its almost certain that you will get a call from a customer about a patient issue or someone who needs a LV right away so they can be discharged for the holiday and you will have to take care of it even if you are on "vacation".