They can try but if you have a bad year with strep throat, pnuemonia, etc etc it could be real easy to go over sick days. If it is real bad like cancer, failing kidneys, liver, etc etc then get FMLA protection. Call HR and get it. If you are just calling out for flu and stomach virus stuff you may be in real trouble. I like coming to work sick as hell and either getting sent home with approval or letting them explain the over-allowed to their boss when they just should have giving me the day off unpaid in the first place.