Medicare 2026

Can Your Part D Plan Drop a Drug Mid-Year? Here's What the Formulary Rules Actually Say

If you take a prescription covered by a Medicare drug plan, it's reasonable to wonder whether that coverage is locked in for the whole year. The short answer: mostly yes, but not entirely. Medicare does allow Part D plans (including the drug coverage built into most Medicare Advantage plans) to update their formularies during the year — but only under specific federal rules, with notice requirements designed to protect people already taking the affected medication.

Here's a plain-English walk-through.

Why formularies change at all

A formulary is the plan's list of covered drugs. Medicare allows plans to update it during the year when drug therapies change, new drugs come to market, or new medical information becomes available. The goal is to keep coverage current — but Medicare also sets guardrails so members aren't blindsided.

Changes that can happen immediately

A plan can remove a drug right away if the FDA says it's unsafe or if the manufacturer pulls it from the market. In those cases, the plan notifies affected members after the change — because waiting wouldn't be safe.

Plans that meet certain requirements can also make immediate substitutions when a lower-cost equivalent arrives:

• Within 30 days of a newly marketed generic, the plan may swap in the generic for the brand-name drug.
• Within 30 days of a newly marketed interchangeable biosimilar — or an unbranded version sold under the same license — the plan may swap it in for the original biological product.

For these immediate substitutions, the new drug must sit on the same or a lower cost-sharing tier, with the same or less restrictive prior authorization, step therapy, or quantity limits. The plan also must have told members in advance (in plan materials) that these substitutions can happen. Written notice to affected members has to go out no later than the end of the month after the month the change takes effect.

Other negative changes: 30 days' notice, or a month's supply

For other changes that work against you — removing a drug you take, moving it to a higher cost tier, or adding restrictions like prior authorization — the plan has two options:

1. Send you written notice at least 30 days before the change takes effect, or 2. When you ask for a refill, give you written notice plus at least a one-month supply under the old rules.

Either way, the notice must name the drug, explain what's changing and why, list alternative drugs on the same or a lower tier with their expected cost sharing, and tell you how to request a coverage determination or exception.

The "quiet period" around enrollment

Here's an important protection many people don't know about: apart from immediate safety removals and the generic/biosimilar substitutions described above, a plan cannot make a negative formulary change that takes effect between the start of the Annual Enrollment Period (October 15) and 60 days after the new plan year begins on January 1. The idea is that when you're shopping, and when you're just settling into a new plan year, the formulary you're comparing should actually be the formulary you get.

What needs Medicare's sign-off

Negative changes beyond the automatic substitutions require CMS review:

• Maintenance changes — for example, changes within 90 days of adding a generic or a non-interchangeable biosimilar, or changes triggered by a new FDA boxed warning or new clinical guidelines — are deemed approved 30 days after the plan submits them.
• Non-maintenance changes require the plan to wait for CMS approval. Even then, members who are already taking the affected drug are exempt from the change for the rest of the plan year.

Your costs can shift even without a formulary change

Two other situations can raise what you pay:

• Your coinsurance (a percentage of the drug's price) can rise if the manufacturer raises the price.
• Your copayment can rise if a generic or biosimilar is added, the original is moved to a higher tier, and you choose to stay on the original brand-name drug or biological product.

In either case, you can ask the plan for an exception.

What to do if you get a notice

• Read it carefully. It will name the drug, explain the change, and list alternatives at the same or lower cost.
• Talk to your prescriber. They can help decide whether an alternative is appropriate — or help you request a coverage determination or exception if staying on your current drug is medically necessary.
• Know the appeals path. If the plan denies an exception, you have the right to appeal.

A few program facts worth knowing for 2027

• The Part D out-of-pocket cap will be $2,400 in 2027 (it is $2,100 in 2026). Once your out-of-pocket drug spending reaches that cap, you pay $0 for covered Part D drugs the rest of the year.
• The maximum Part D deductible a plan may charge in 2027 is $700.
• The Part D base beneficiary premium for 2027 is $41.33 — a national figure used to calculate the late-enrollment penalty. Actual plan premiums are set plan by plan.
• Annual Enrollment runs October 15 – December 7, 2026, with choices effective January 1, 2027.
• Social Security announced a 3.6% COLA for benefits payable starting January 2027.
• The 2027 Part B standard premium and deductible, and the 2027 IRMAA income brackets, have not been announced yet. CMS announces those in the fall, usually in November.

Extra Help and Medicaid: more flexibility to change plans

Since 2025, people with Medicaid or Extra Help have a monthly Special Enrollment Period to move to Original Medicare paired with a stand-alone Part D plan, or to switch stand-alone Part D plans. Full-benefit dual-eligible individuals can also join an integrated Dual Eligible Special Needs Plan (D-SNP) in any month. So if a mid-year formulary change doesn't work for you and you qualify for this help, you may have more options than the general Medicare population.

Where to go next

For specifics on your drugs, your plan's formulary, and what's available where you live, use the Plan Finder tool at Medicare.gov or call 1-800-MEDICARE (1-800-633-4227), TTY 1-877-486-2048, 24 hours a day, 7 days a week. These are the official sources for comparing coverage and understanding your rights.