Exception | Medicare GlossaryMedicare Glossary Topic.
A Medicare Prescription Drug Plan decision in response to your written request about prescription drug coverage. A formulary exception is the plan's decision to cover a drug that is not on the drug list (formulary) or to waive a coverage rule. A tier exception is the plan's decision to lower the amount for a drug that is not in a preferred drug tier. Your doctor or prescriber must provide a supporting statement along with your request for the exception that states the medical reason for the exception.