All in a day's work.

CMS rules regarding what constitutes a patient day are inconsistent and often confusing. Hospitals and their advisers should have a clear understanding of CMS's rules regarding what constitutes a patient day, the impact of those rules on Medicare payment, and instances in which CMS's rules may be subject to challenge. Lack of familiarity with the finer points of these rules may result in substantial underpayments for services rendered.