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Medicare Part D Formulary Changes: What to Do Next

Medicare Part D formulary changes can happen mid-year, and knowing what to do protects your access and your budget.

This alert explains why plans make changes, how to respond if your drug moves tiers or is no longer covered, what’s coming with 2026 Inflation Reduction Act pricing, and step-by-step help using Medicare.gov’s Plan Finder so you can compare plans for your prescriptions.

Why Part D formularies change mid-year

A formulary is your plan’s list of covered drugs and the cost-sharing tiers they’re on. Plans can update formularies during the year for reasons like safety concerns, new generics entering the market, manufacturer price changes, and FDA actions, as long as they follow Medicare rules and use a Pharmacy & Therapeutics (P&T) committee to guide decisions. See Medicare’s formulary requirements in the CMS manual for details (CMS Part D Manual, Ch. 6).

If a change impacts you—like moving your drug to a higher tier, adding utilization rules (prior authorization, step therapy), or removing it—plans generally must give you advance written notice or provide a one-time transition fill at the pharmacy while you and your doctor consider alternatives (Medicare.gov: What Part D plans cover).

Tier changes are common when a lower-cost generic or therapeutic alternative becomes available. Plans may encourage use of the lower-cost option, but you still have rights: you can request a tiering or formulary exception if your doctor supports medical necessity for your current medication.

What to do when your drug moves tiers or is removed

Stay calm, but act promptly. When you receive a notice or see a change at the pharmacy, follow these steps to avoid gaps in therapy or surprise costs:

  • Review the plan’s letter or pharmacy message carefully. It should name the change, the effective date, and any alternatives the plan suggests.
  • Ask your pharmacist about a transition fill. If the change is sudden, many plans allow a one-time temporary supply so you have time to decide next steps (CMS Transition Requirements).
  • Call your prescriber. Discuss whether a covered alternative or new generic is appropriate for you. If not, ask about supporting an exception request.
  • Consider a tiering exception if your drug is still on the formulary but at a higher tier. If approved, you’ll pay the cost share of a lower tier for that drug. Note: Medicare doesn’t require plans to grant exceptions for specialty-tier drugs (Medicare.gov: Coverage decisions & exceptions).
  • Consider a formulary exception if your drug is no longer covered or has new restrictions. Your doctor must explain why alternatives won’t work for you.
  • Appeal if needed. If your exception is denied, you can appeal through multiple levels. Standard decisions are typically due in 72 hours; expedited decisions in 24 hours when delay could affect your health (Medicare.gov: Part D appeals).

How to request a formulary or tiering exception

You or your prescriber can start by asking the plan for a coverage determination. The easiest path is to have your prescriber submit the request electronically using the standard CMS form and clinical notes that show why you need that drug or a lower tier.

  • Call your plan’s Member Services for instructions and the right form. Look on the back of your ID card.
  • Ask your prescriber to include: prior drug trials and outcomes, allergies, contraindications, and why alternatives could be unsafe or ineffective.
  • Request an expedited review if waiting could seriously harm your health.
  • Follow up. If approved, confirm the new copay and authorization period. If denied, ask for the denial letter and file an appeal by the deadline.

Learn more in Medicare’s official guidance on coverage decisions and exceptions (Medicare.gov).

Use Medicare.gov Plan Finder to compare drug costs

If your costs jump after a formulary change—or you want to be proactive—use the official Medicare.gov Plan Finder to compare total costs across plans for your drugs and pharmacies.

Step-by-step: Find a better Part D fit

  • Go to Medicare.gov/plan-compare.
  • Select “Continue without logging in” or sign in for a personalized search if you have a Medicare account.
  • Enter your ZIP code, then choose whether you get help with costs (Medicaid, Extra Help/Low-Income Subsidy) to see accurate pricing.
  • Add your exact medications and dosages, then select your preferred pharmacies (retail and mail-order).
  • Sort by “Lowest drug + premium cost” to see your total annual cost, not just the monthly premium.
  • Open the plan details page to review each drug’s tier, prior authorization or step therapy rules, and the estimated monthly costs across the year.
  • Save your Drug List ID for easy updates later, and print or download the comparison for your records.

Tip: If you’re mid-year and considering a change, you may need a Special Enrollment Period (SEP). Certain events—like moving, losing other coverage, or qualifying for Extra Help—can open an SEP; otherwise, changes wait until Medicare’s Open Enrollment (Oct 15–Dec 7) for coverage effective Jan 1 (Medicare enrollment periods).

2026 IRA pricing changes: what to expect

The Inflation Reduction Act (IRA) is reshaping Medicare drug costs. Several key protections are already in place, and more are coming that could influence formulary tiers and pricing strategy.

  • Now: Many adult vaccines are $0 under Part D, and most insulin is capped at $35/month (Medicare.gov: Vaccines; Medicare.gov: Insulin).
  • 2024–2025: Catastrophic coinsurance has been eliminated in 2024, and a $2,000 annual out-of-pocket cap begins in 2025, with an option to spread payments over the year via the Prescription Payment Plan (CMS: IRA Drug Provisions).
  • 2026: Medicare’s first negotiated “maximum fair prices” for a set of high-spend Part D drugs take effect. While not every drug will be negotiated, these prices can lower plan and beneficiary costs and may shift how plans structure tiers for affected drugs (CMS: Drug Price Negotiation Program; KFF explainer).

Bottom line: Keep an eye on your specific meds each fall during Open Enrollment. Even as IRA savings roll out, plan formularies and preferred pharmacies can change, affecting what you pay.

Smart habits to avoid surprises

  • Make an annual “med check.” Each October, run your drugs through Plan Finder and look for lower total cost options.
  • Keep a current medication list (names, strengths, dosing) in your wallet or phone to speed up comparisons and exception requests.
  • Use preferred pharmacies in-network when possible; prices can differ widely by location.
  • Ask about 90-day supplies or mail order for maintenance meds if allowed—it can lower tier copays.
  • If your income is limited, apply for Extra Help (LIS) to reduce premiums and drug costs.

Take action now

If your Medicare Part D formulary changed—or you just want to ensure you’re not overpaying—compare plans based on your prescriptions and pharmacies. Start here: Medicare.gov Plan Finder. You can also get free, unbiased counseling from your local State Health Insurance Assistance Program (SHIP): SHIP locator.

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