Creditable Coverage
  
Creditable coverage is a type of health coverage plan, usually a prescription drug plan. It provides protection for those individuals with pre-existing conditions, such that if they change their insurance coverage, their pre-existing condition will still be covered. Or, at least...they won’t have to wait as long for it to be covered.
The topic of creditable coverage is a bit glum, but pre-existing conditions actually encompass a lot more than what you may realize. For example, that horrible acne you had in middle school could actually qualify as a pre-existing condition. Because of creditable coverage, your expensive medication to combat crater face is still available, even after a change in insurance policies.