When a single prescription costs thousands of dollars a month, Medicare open enrollment stops being routine paperwork. Between October 15th and December 7th, 2026, anyone with Medicare can switch drug plans or move between Original Medicare and Medicare Advantage, and the new coverage starts January 1st (Medicare.gov). If you do nothing, your current coverage continues automatically, which is fine only if nothing about it changed for your drug.
1. Read Your Plan's Annual Notice of Change for Your Drug
Every Part D and Medicare Advantage plan has to mail members an Annual Notice of Change by September 30th (42 CFR 423.2267). It lists what changes in January: premiums, deductibles, which drugs are covered, and the rules attached to them.
Open it and find your drug by name. Four things decide what 2027 costs you: whether the drug is still on the formulary (the plan's list of covered drugs), which tier it sits on, whether it newly needs prior authorization or step therapy (trying a cheaper drug first), and which pharmacies can fill it. That last one catches rare disease patients more than anyone. Plenty of rare disease drugs ship from only one or a handful of specialty pharmacies; Galzin for Wilson disease, for one, is dispensed through a single specialty pharmacy. A plan that covers your drug but not your pharmacy is a plan that doesn't really cover your drug.
2. Put Every Drug Into Medicare Plan Finder, With Your Pharmacy
Medicare's Plan Finder lets you enter each prescription and your preferred pharmacies, then estimates your total yearly out-of-pocket cost plan by plan (Medicare.gov, Your Yearly Medicare Review). Enter the exact drug and strength, the specialty pharmacy you use, and anything else you take. Ranking plans by premium alone is the classic mistake, since a $0 premium plan that puts your drug in a 25% coinsurance tier can cost far more than a plan with a premium and better coverage for that one drug.
Print or save the result for the plan you choose. If something goes wrong in January, a record of what the plan showed in November helps when you call.
3. The 2027 Part D Cap Is $2,400, and Rare Disease Drugs Can Reach It in January
CMS set the 2027 Part D out-of-pocket threshold at $2,400 and the maximum deductible at $700, up from $2,100 and $615 in 2026 (CMS 2027 Rate Announcement). Your deductible and your share of each fill both count toward the $2,400. Once you reach it, Medicare's catastrophic coverage starts and you pay nothing for covered Part D drugs for the rest of the calendar year (Medicare.gov).
For a specialty drug with a list price in the thousands, one January fill can use up the whole $2,400. The cap resets every January 1st, so a rare disease patient on an expensive pill can expect to pay the full amount early in the year, every year.
Spreading the $2,400 With the Medicare Prescription Payment Plan
Every Part D plan has to offer the Medicare Prescription Payment Plan. It is voluntary and free, and instead of paying the pharmacy, you get a monthly bill from your plan (Medicare.gov). It doesn't lower what you owe; it spreads it out. If you'd otherwise owe the full $2,400 in January, spreading it over 12 monthly bills works out to about $200 a month.
You can sign up for 2027 during open enrollment by contacting the plan, and the rule requires plans to accept opt-ins before the year starts (42 CFR 423.137). If you're already in the payment plan and stay with the same Part D plan, it renews automatically for 2027. If you switch plans, it ends, and you have to sign up again with the new plan (Medicare & You 2027).
4. Infused Rare Disease Drugs Usually Fall Under Part B, Where Original Medicare Has No Cap
The $2,400 cap covers Part D drugs only, whether you get Part D as a separate plan or inside a Medicare Advantage plan (also called Part C). Drugs given by a clinician, like infusions at a doctor's office or hospital outpatient center, are usually covered by Part B instead (Medicare.gov). That includes many infused enzyme replacement therapies and infused antibody drugs. Under Part B you pay up to 20% of the Medicare-approved amount after the Part B deductible, which is $283 in 2026 (CMS).
For someone on an infused drug, this choice matters more than which Part D plan to pick. Medigap has its own enrollment rules, so talk to your State Health Insurance Assistance Program before dropping a Medigap policy or leaving Original Medicare.
5. Your Protections If a New Plan Doesn't Cover Your Drug
Switching plans doesn't mean going without. In the first 90 days of a new plan, a drug you already take that isn't on the new formulary, or that needs prior authorization or step therapy, must be covered with a one-time temporary supply of at least a month (42 CFR 423.120). Medicare.gov calls it a transition fill and describes it as a 30-day supply. The plan then has to send you a written notice within 3 business days.
Use that month to ask for a formulary exception. Your prescriber sends the plan a statement of medical need, and the plan must decide within 72 hours, or 24 hours if waiting could seriously harm your health. The clock starts when the plan receives the prescriber's statement, not when you first call, so ask your doctor's office to send it the same day (Medicare Appeals booklet, 2026). If the answer is no, our guide to appealing a rare disease drug denial walks through the next steps.
6. Copay Cards Don't Work With Medicare, but Charity Funds Can
Drugmaker copay cards that bring a specialty drug down to $0 for privately insured patients can't be used for drugs paid for by Medicare. Federal rules treat them as a possible kickback when the government is paying, which is why copay card terms exclude Medicare, Medicaid and TRICARE (HHS Office of Inspector General, 2014).
Two other kinds of help do accept Medicare. Independent charity funds help insured patients with copays and premiums, and some funds take only people with government coverage. When we checked on September 24th, 10 open disease funds at TotalAssist and HealthWell required Medicare, Medicaid or TRICARE. Some drugmakers also run separate free-medicine foundations that accept Medicare patients who meet income limits; the Bristol Myers Squibb Patient Assistance Foundation, for one, lists Camzyos for Medicare patients who have spent at least 3% of household income on prescriptions this year. Our patient assistance finder shows only the programs that fit Medicare when you pick it as your insurance.
7. Check Whether You Qualify for Extra Help
Extra Help, also called the Low-Income Subsidy, pays part of Part D premiums, deductibles and copays. In 2026, the limits are $23,940 in income and $18,090 in resources for one person, or $32,460 and $36,100 for a married couple (Medicare.gov). In 2027, people with Extra Help pay no more than $5.80 for a generic drug or $14.40 for a brand-name drug, and nothing once their drug costs reach $2,400.
Apply through Social Security at ssa.gov/medicare/part-d-extra-help or by calling 1-800-772-1213. Applications are accepted any time of year, not only during open enrollment.
8. Get Free Medicare Help Before December 7th
Every state has a State Health Insurance Assistance Program, a free counseling service funded by the federal government to give objective help choosing a plan, comparing costs and handling appeals (Administration for Community Living). Find yours at shiphelp.org. You can also call 1-800-MEDICARE (1-800-633-4227), or enroll directly through Plan Finder or the plan itself.
Rare disease patients have one more resource most people don't. The drugmaker's patient support line, listed for every approved drug in our patient assistance finder, handles Medicare coverage for that one drug every day, and many of these programs will check how a specific plan covers the drug. Call before you switch, not after.
If Medicare Isn't Your Only Insurance, From a Spouse's Job, COBRA or Disability
Plenty of people with a rare disease have Medicare and a second plan, often through a spouse's job, and the order in which the two pay changes almost everything above. Medicare's guide to who pays first sets the rules by age, job status and employer size (Medicare, Who Pays First, 2026).
- 65 or older, covered through your or your spouse's current job
- If the employer has 20 or more employees, the job plan generally pays first and Medicare pays second. With fewer than 20, Medicare pays first.
- Under 65, on Medicare because of a disability
- The line moves to 100 employees. At 100 or more, the job plan pays first; below that, Medicare pays first. Coverage from a former employer never counts, so Medicare pays first.
- Medicare because of kidney failure (ESRD)
- The job or retiree plan pays first for a coordination period of up to 30 months, whatever the employer's size.
When a spouse's current job plan pays first, there's a real advantage. You can usually wait to sign up for Part B and sign up later without a late penalty: any time while that coverage continues, or within 8 months after the job or the coverage ends, whichever comes first (Medicare & You 2027). If the job plan's drug coverage is creditable, meaning Medicare counts it as at least as good as a standard Part D plan, you can also hold off on Part D without a penalty. The plan has to tell you each year whether it is.
Copay cards are the gray area. The Inspector General's guidance applies when a federal program pays for a drug "in whole or in part," and cards typically exclude anyone covered by a federal program (HHS Office of Inspector General, 2014). Whether a card works when the job plan pays and Medicare is never billed for that prescription comes down to that card's terms, so ask the drugmaker's support line before counting on it.
COBRA doesn't count as job coverage for Medicare
If you have Medicare because of age or disability, Medicare pays first and COBRA pays second. If you're eligible for Medicare but haven't enrolled, COBRA "may only pay for a small portion" of your care, leaving most of the bill to you (Medicare.gov). The Department of Labor adds that a plan can apply Medicare as the primary payer even if you never signed up.
A patient on disability with a spouse on COBRA
Social Security disability benefits bring Medicare automatically after 24 months of benefits, with no waiting period for ALS (Social Security Administration, 2026). Once the patient has Medicare, Medicare pays first and COBRA second.
Two COBRA rules matter for this family. COBRA can end for a family member who becomes entitled to Medicare after choosing COBRA, though it continues for everyone else on it, and it continues for a person who already had Medicare Part A before choosing it (Department of Labor). COBRA can also run 29 months instead of 18 when Social Security finds that a family member's disability began before or within the first 60 days of COBRA, as long as the plan hears about the decision within 60 days and before the 18 months end. If COBRA includes creditable drug coverage, the end of COBRA opens a window to join a Medicare drug plan without a penalty (Medicare.gov).
3 Medicare Situations That Catch Rare Disease Patients in January
The plan still covers your drug, but not your specialty pharmacy
A drug sold through 1 or 2 specialty pharmacies is only as covered as the plan's pharmacy network. If the pharmacy that has shipped your drug for years isn't in the new plan's network, the first January refill can stall even though the drug itself is on the formulary. Before you enroll, call the plan and ask by name whether your specialty pharmacy is in network for 2027.
What that looks like for one acromegaly patient
Take a woman with acromegaly who has had Somatuline Depot shipped by the same specialty pharmacy for 3 years. In November she picks a new plan because its premium is $40 a month lower and the drug shows as covered. Her first 2027 refill is rejected on January 4th: the pharmacy is out of network. The plan's own specialty pharmacy needs a new prescription, a new prior authorization and 7 to 10 days to set up shipping, and her injection is due on January 9th. The $480 she saved on premiums costs her a missed dose. The question that would have prevented it takes 2 minutes on the phone: is this pharmacy in your 2027 specialty network for this drug?
Suppose she asked, switched plans with her eyes open, and got the January 9th dose on time. Here is how the rest of 2027 plays out, and it is a different year from the one she just had.
January is the expensive month. Her plan puts Somatuline Depot in a coinsurance tier, so the first fill takes her deductible plus 25% of a drug that lists for thousands of dollars, and she reaches the $2,400 cap on that one shipment. From then on her Part D drugs cost her nothing for the rest of the year. If she signed up for the Medicare Prescription Payment Plan before January 1st, the same $2,400 arrives as 12 monthly bills of about $200 instead of one January bill.
The cap doesn't cover everything she pays for. Her endocrinologist visits, the IGF-1 blood tests every few months and the pituitary MRI fall under Part B, where Original Medicare charges 20% with no yearly limit. A generic drug from a different plan, say for blood pressure, counts toward the same $2,400 cap, so it is free too once she hits it.
By late September the letters arrive again. Her plan's Annual Notice of Change for 2028 could move Somatuline Depot to a different tier, add a step-therapy rule requiring a cheaper octreotide first, or drop the specialty pharmacy she just switched to. The same 2-minute call in November 2027 is what keeps 2028 from starting the way 2027 almost did. If her income changed during the year, she also checks whether she now qualifies for Extra Help, which would bring her January bill down to $14.40 per brand-name fill.
Two things can change the picture mid-year. If a generic lanreotide is on her plan's formulary at a lower tier, the pharmacy may substitute it, and she should ask her doctor whether that is fine for her. If her doctor moves her to an oral option like Palsonify, the cap and the network questions start over for the new drug, though she doesn't have to wait until open enrollment to fill it: a new prescription on a covered drug can start any time, and a formulary exception covers one that isn't.
A $0 premium plan, then a $2,400 pharmacy bill
Low-premium plans often put expensive drugs in a coinsurance tier, so the whole year's $2,400 can come due at the first fill. Nothing is wrong with the plan; the money simply arrives in January instead of spread across premiums. If that timing would be hard, sign up for the payment plan before January 1st rather than at the pharmacy counter.
“This payment option might help you manage your monthly expenses, but it doesn't save you money or lower your drug costs.”
Medicare.gov, on the Medicare Prescription Payment Plan
Moving to Medicare Advantage while on an infusion
Medicare Advantage can make sense for an infused drug because of the yearly cap on medical costs, but the plan's network and approval rules replace Original Medicare's. Confirm that your infusion center and the specialist who orders the drug are in network, and ask whether the drug needs the plan's approval before the first 2027 dose. An infusion scheduled for January 3rd is the one most likely to be delayed by a missing approval.
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Common Questions About Medicare and Rare Disease Drugs
What is the Medicare Part D out-of-pocket maximum for 2027?
$2,400. Once your deductible and your share of covered Part D drugs reach $2,400 in 2027, you pay nothing more for covered Part D drugs for the rest of the year. The 2026 cap is $2,100.
Can I use a drug company copay card with Medicare Part D?
No. Drugmaker copay cards exclude Medicare, Medicaid and TRICARE because federal rules treat them as a possible kickback when a government program pays for the drug. Independent charity funds and some drugmaker free-medicine foundations do accept Medicare patients.
What happens if my new Medicare drug plan doesn't cover my rare disease drug?
In the first 90 days of a new plan, the plan must give you a one-time temporary supply of a drug you already take, usually 30 days. Use that time to have your prescriber request a formulary exception; the plan must decide within 72 hours of getting the prescriber's statement, or 24 hours if the request is expedited.
Are infusion drugs covered by Medicare Part B or Part D?
Drugs given by a clinician, like infusions at a doctor's office or hospital outpatient center, are usually covered by Part B, where you pay up to 20% after the Part B deductible. The Part D cap does not apply to them, and Original Medicare has no yearly limit on that 20% unless you have Medigap or a Medicare Advantage plan.
Does Medicare pay first if I have insurance through my spouse's job?
It depends on your age and the employer's size. If you're 65 or older and the coverage comes from your spouse's current job at an employer with 20 or more employees, the job plan generally pays first. If you're under 65 and on Medicare because of a disability, the employer needs 100 or more employees for the job plan to pay first.
Should I delay Medicare Part B if I have COBRA?
Generally no. COBRA doesn't count as coverage from current employment, so it doesn't give you a special window to sign up for Part B later, and you may face a gap and a lifetime late penalty. Your 8 months to sign up without a penalty start when the job-based coverage ends, whether or not you choose COBRA.
Is Medicare Advantage the same as Medicare Part C?
Yes. Medicare Advantage is the common name for Part C, private plans that replace Original Medicare's Part A and B coverage and usually include Part D drug coverage. They cap what you pay each year for in-network medical care; the highest cap allowed in 2027 is $9,850.
Can I sign up for the Medicare Prescription Payment Plan for 2027 during open enrollment?
Yes. Contact your Part D plan or its website; plans must accept sign-ups before the plan year starts. If you are already enrolled and keep the same plan, it renews automatically, but switching plans ends it and you need to sign up again with the new plan.
Medicare's own advice is that if you're happy with your coverage, you don't need to do anything. For a rare disease drug, being happy with it in 2026 isn't enough; the thing to confirm, in writing, is that your drug, its tier and your pharmacy all carry over into 2027.