Medicare Part D denied a drug behind a step-therapy requirement? What the rule says and how to appeal.
Checked against the current rules on September 23, 2026.
A denial for a drug behind a step-therapy requirement isn't the end of the story — Medicare Part D plans have to follow specific coverage rules, and a denial that doesn't square with those rules is exactly the kind of appeal that tends to win.
Here's what the rule actually requires, what evidence usually turns a denial around, and the deadline you're working against.
What the rule requires
Coverage for a drug behind a step-therapy requirement under a Medicare Part D plan is governed by§ 423.578 Exceptions process.. A Medicare Part D plan generally cannot apply a stricter test than what these rules require.
Questions that decide it
Before you appeal, these are the facts that usually decide whether a denial like this holds up:
Has the patient already tried the required first-step drug?
Did the first-step drug not work, or cause a side effect?
Does the patient have a medical reason (an allergy, an interaction with another medication, a condition) that the first-step drug is not safe to try at all?
What a winning appeal has to show
An appeal that wins usually includes:
Records of the required first-step drug's own trial — dates, dose, and outcome — §423.578(b) treats a step-therapy requirement as a formulary-use tool subject to the same exceptions process as an off-formulary drug — showing the step was already tried (and failed, or wasn't tolerated) is the core evidence. (Your doctor's office provides this.)42 CFR 423.578
Chart documentation of a contraindication or expected adverse reaction to the first-step drug, if the step was never tried — The exceptions process doesn't require literally trying a drug that's medically contraindicated — but the contraindication itself has to be documented. (Your doctor's office provides this.)42 CFR 423.578
Your deadline to appeal
No deadline to make this first request — it's your initial ask, not yet an appeal. The 65-day appeal clock only starts once the plan denies it.42 CFR 423.566
The plan itself then has its own clock to decide. 72 hours for a standard drug-benefit request (24 hours if expedited). For an exception request, the clock instead runs from receipt of your prescriber's supporting statement — 72 hours standard / 24 hours expedited from that point, or from the end of a 14-day wait if the plan never receives one. Payment requests: 14 calendar days (42 CFR § 423.568, § 423.570, § 423.572).
What to ask your doctor to address
If you're asking the treating physician for a supporting letter, it should speak to:
The first-step drug's own trial dates, dose, and why it failed or wasn't tolerated — or the specific contraindication if it was never tried.42 CFR 423.578
Why the requested drug, specifically, is needed now for this diagnosis.42 CFR 423.578
Questions people ask
- Can the plan just say it's "not medically necessary" with no further explanation?
- The denial notice has to explain the basis for the decision and tell you how to appeal. If it doesn't point to a specific rule or criteria, that's itself worth raising in your appeal — you're entitled to know what standard was applied.
- What if I don't have all the evidence listed above?
- Include what you have. An appeal with partial evidence and a clear explanation of the rule still gets a real review — it doesn't need to be complete to be worth filing.
Sources — last checked September 23, 2026
- § 423.578 Exceptions process.as of September 23, 2026
- 42 CFR 423.566as of September 23, 2026
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By CaseWhy Appeals editorial. See how this content is produced. Not legal advice. Not affiliated with or endorsed by Medicare, CMS, or any health plan. A product of CaseWhy LLC.
