Frequently Asked Questions
What is a Medicare Part D formulary?
A formulary is the list of prescription drugs covered by your Medicare Part D plan, organized into cost tiers. Each drug is assigned to a tier — lower tiers (generic, preferred brand) have lower copays; higher tiers (non-preferred brand, specialty) have higher copays or coinsurance. Your plan's formulary also shows whether a drug requires prior authorization, step therapy, or quantity limits.
How do I find my Part D formulary?
Your Part D plan is required to provide a formulary. Access it online at your plan's website (search for 'formulary' or 'drug list'), call your plan's member services number, or use Medicare.gov Plan Finder which has formulary search built in. Formularies are updated regularly — check annually in September when plans publish their upcoming year's formulary.
What do Part D drug tiers mean?
Tier 1: Preferred generics — lowest copay ($0–$5). Tier 2: Non-preferred generics — low copay ($5–$15). Tier 3: Preferred brand names — moderate copay ($30–$50). Tier 4: Non-preferred brands — higher copay ($65–$100+). Tier 5: Specialty drugs — 25–33% coinsurance, can be hundreds per month. Your drug's tier determines your monthly cost.
What is step therapy in Medicare Part D?
Step therapy (also called fail-first) requires you to try a lower-cost drug before your plan covers the higher-cost drug your doctor prescribed. For example, your plan may require trying generic metformin before covering brand-name Jardiance for diabetes. Your doctor can request a step therapy exception if the first-step drug is medically inappropriate for you.
What is a formulary exception?
If your drug isn't on the formulary or is on a higher tier than expected, you can request a formulary exception — asking the plan to cover the drug or cover it at a lower tier. Your doctor must submit documentation that the drug is medically necessary and that alternatives on the formulary are not appropriate for you. Medicare plans must respond within 72 hours (24 hours for expedited requests).
Your Part D formulary determines whether your medications cost $10/month or $400/month — and most seniors never look at it until they get a surprise bill at the pharmacy. Understanding your formulary takes 15 minutes and can save hundreds of dollars annually. Here is exactly how to read and use it.
The Tier System Explained
Every Part D formulary organizes drugs into tiers — usually 5 or 6. Your copay depends on which tier your drug lands on:
| Tier | Drug Type | Typical Copay |
|---|---|---|
| Tier 1 | Preferred generics | $0–$5 |
| Tier 2 | Non-preferred generics | $5–$15 |
| Tier 3 | Preferred brand names | $30–$50 |
| Tier 4 | Non-preferred brands | $65–$100+ |
| Tier 5 | Specialty drugs | 25–33% coinsurance |
How to Check Your Specific Drug
- Go to your plan's website or Medicare.gov Plan Finder
- Navigate to the formulary or drug search tool
- Enter your drug name (brand or generic), dosage, and quantity per month
- Note the tier, copay, and any coverage restrictions (PA, step therapy, quantity limits)
- Check your preferred pharmacy — copays can differ between preferred and non-preferred pharmacies
Coverage Restrictions — What They Mean
Prior Authorization (PA): Your doctor must submit clinical documentation before the plan covers the drug. PA approval is required before you fill the prescription.
Step Therapy (ST): You must first try and fail a lower-cost alternative before the plan covers the requested drug.
Quantity Limits (QL): The plan only covers a set number of pills, patches, or injections per month — even if your doctor prescribed more.
Requesting a Formulary Exception
If your drug isn't covered or is on a tier higher than expected, you can request an exception. Your doctor submits a statement explaining why you need this specific drug and why alternatives won't work. Standard response: 72 hours. Expedited (urgent): 24 hours. Approved exceptions may add the drug to your formulary or reduce its tier — resulting in lower copays. When exceptions are denied, you have the right to appeal.
Annual Formulary Review — Do This Every October
Formularies change every January. A drug covered at Tier 1 this year may move to Tier 3 next year. Your plan mails an Annual Notice of Change in September — check whether any of your medications changed tiers or were removed. Use Medicare.gov Plan Finder during AEP (October 15–December 7) to compare whether a different plan would cover your drugs at lower cost.
- Look up every medication on your plan's formulary today — not at the pharmacy
- Note any PA, step therapy, or quantity limits for each drug
- Check the Annual Notice of Change every September for formulary changes
- If a drug moves to a higher tier, request a tier exception from your doctor
- Use GoodRx as a price check — sometimes cash price is lower than your copay