Part D Step Therapy Exception: How to Skip the Required Trial Drugs

What Step Therapy Means for Your Parent

Step therapy is a formulary restriction that forces your parent to try one or more cheaper medications before the plan will cover the drug their doctor actually prescribed. The plan marks these drugs with an "ST" flag in the formulary.

The logic from the plan's perspective: if a $15 generic works, there's no medical reason to pay for a $300 brand-name drug. The problem from a caregiver's perspective: your parent may have already tried those cheaper alternatives years ago, had adverse reactions, or has a clinical reason why only the prescribed drug works. Starting over with a trial-and-fail cycle wastes time and risks medical complications.

You don't have to accept step therapy. Federal rules give your parent the right to request a formulary exception.

How to File the Exception

1. Request a Coverage Determination

Submit a written request to the plan's pharmacy coverage department using Form CMS-10146 (the standard model Coverage Determination request form, available on cms.gov). You can also write a detailed letter instead — the form isn't legally required, but it ensures you hit every element the plan reviews.

2. Get the Physician's Clinical Statement

This is the piece that determines whether the exception succeeds. The prescribing doctor must submit a statement to the plan explaining:

• The patient's diagnosis and why this specific drug is needed
• Which formulary alternatives have been tried, when, and why they failed or are clinically inappropriate
• Whether the alternatives caused documented adverse reactions (with dates, severity, and clinical outcomes)
• Why switching to or restarting a step therapy alternative would put the patient at medical risk

Generic language may not establish the exception. A detailed statement such as "Patient was prescribed Drug A from 2019 to 2022, developed severe hepatotoxicity requiring hospitalization at [facility] on [date], and cannot safely resume this drug class" gives the plan the clinical information it needs to evaluate the request.

3. Wait for the Decision

• Standard timeline: 72 hours from when the plan receives the physician's supporting statement.
• Expedited timeline: 24 hours, available when the physician certifies that waiting 72 hours would seriously jeopardize the patient's life, health, or ability to regain function.

What Happens If the Exception Is Denied

A denied exception is not the final answer. You can:

1. Request a redetermination — the plan's internal appeal. File within 65 days of the denial. The plan has 7 days (standard) or 72 hours (expedited) to decide.
2. Escalate to the Independent Review Entity — if the plan upholds its denial, an independent contractor (C2C Innovative Solutions) reviews the case. File within 60 days. Decision timeline: 7 days standard, 72 hours expedited.
3. Continue through the five-level appeals process if needed.

At each level, submit additional clinical documentation. A letter from a specialist carries more weight than a primary care physician's note for condition-specific medications.

The Transition Supply Bridge

If your parent just switched to a new plan and the prescribed medication hits a step therapy wall, the plan must provide at least one temporary 30-day supply for a retail fill while you file the exception. This gives you time to file the exception without a gap in medication.

Avoiding Step Therapy Before It Starts

During open enrollment, check the formulary of any plan you're considering for ST flags on your parent's medications. If a top-ranked plan imposes step therapy on a critical drug and you already know the alternatives won't work, weigh whether the total cost savings justify the administrative fight — or whether a slightly more expensive plan without that restriction is worth the peace of mind.

Our Medicare Part D guide includes a formulary exception letter template that walks through the clinical documentation format plans expect.

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