Medicare.gov

Drug plan rules

Medicare drug plans may have rules for if and how they cover drugs. These rules can be called:

When your drug coverage begins you may get a transition fill, a one-time, 30-day supply of a drug you’ve been taking that your plan either doesn’t cover or requires prior authorization/step therapy.

Check with your plan to find out their specific coverage rules.

Prior authorization

Prior authorization is approval based on specific criteria that you and/or your prescriber  must get from your plan, before your plan will cover certain drugs. Your prescriber may need to show that the drug is medically necessary for the plan to cover it.

Plans may also use prior authorization when they only cover a drug for certain medical conditions, but not others. When this occurs, plans will likely have other drugs on their drug list (formulary) for the other medical conditions that your prescriber is using the drug to treat.

You or your prescriber can contact your plan to ask for an exception to prior authorization. An exception is when a drug plan decides to cover a drug that's not on its drug list, or to waive a coverage rule. You or your prescriber must request an exception, and your doctor or other prescriber must provide a supporting statement explaining their belief that: 

  • Because of your medical condition, it’s medically necessary for you to be on the drug, even if you don’t meet the plan’s prior authorization requirements.
  • You’ll have negative health effects if you take a different drug.
  • A different drug would be less effective.

Step therapy

Step therapy is a rule that requires you to try a less expensive drug on the plan’s drug list (formulary) that’s been proven effective for most people with your condition before you can move up a “step” to a more expensive drug. Some plans may require you to try: 

  • A generic drug or a biosimilar  (if available)
  • A less expensive brand-name drug or biological product on their drug list (formulary) 

You or your prescriber can contact your plan to ask for an exception to step therapy. Your prescriber must give a statement supporting the request, which includes their belief that:

  • Because of your medical condition it’s medically necessary for you to be on a more expensive drug without trying the less expensive drug first.
  • You’ll have adverse health effects if you take the less expensive drug.
  • The less expensive drug would be less effective. 

Can I see an example of an exception to step therapy? 

If the exception is approved, your plan will cover the more expensive drug, even if you didn’t try the less expensive drug first. 

Quantity limits

Plans may limit the amount of drugs they cover over a certain time period, for safety and cost reasons. For example, a plan may only cover 30 tablets of a drug per month.

You or your prescriber can contact the plan to ask for an exception if your prescriber believes that, because of your medical condition, a quantity limit isn’t medically appropriate (for example, your doctor believes you need a higher dose).