How to check a rare-disease drug is covered before you enroll in a 2027 plan

Most Part D formularies did not list the newest kidney and complement medicines in 2026, so the plan decision is a coverage decision. Four checks, the deadlines, and what to do if no plan lists your drug.

Quick answer: how do you check a rare-disease drug before you enroll?

When can you change plans for 2027?

Medicare open enrollment for 2027 runs October 15 to December 7, 2026, and Medicare.gov says the plan must get your request to join by December 7 for changes to start January 1. Marketplace (HealthCare.gov) open enrollment starts November 1; enrolling or changing by December 15 starts coverage January 1, and enrolling from December 16 through January 15 starts it February 1.

Step 1: find your drug on each plan's 2027 formulary

A plan's formulary is its list of covered drugs, and for a rare-disease medicine the first question is simply whether the drug is on it. In the 2026 data, Rhapsido appeared on 36 of 328 Part D formularies and Empaveli on 27, so four out of five plans you could pick did not list them at all.

Search by the exact product, strength and form, because a plan can list one form and not another. Medicare Plan Finder is the official per-plan lookup. The OmniRx formulary checker runs the same CMS file across every plan in your state at once, and the insurer pages for Humana 2027, UnitedHealthcare 2027 and Medicare Part D 2027 explain each insurer's tiers.

Step 2: read the tier, prior authorization, step therapy and quantity limits

Restrictions decide how hard the drug is to get even when it is listed. Prior authorization means your prescriber must show the plan why you need it before the first fill. Step therapy means trying a cheaper drug first. A quantity limit caps how much the plan pays for per fill. In the 2026 data none of the five kidney and complement medicines above carried step therapy, but almost every listing carried PA, and specialty-tier placement was common: Fabhalta sat on the specialty tier (tier 5) on 23 of the 29 formularies that listed it.

Our specialty drug coverage guide explains tiers in depth; this page is the procedure to run before you sign.

Step 3: price it with the 2027 deductible and the $2,400 cap

A Part D plan's 2027 deductible can be no more than $700, and after it you pay coinsurance until your out-of-pocket spending on covered Part D drugs reaches $2,400; then you pay nothing more for covered drugs that year (Medicare.gov drug costs). The cap only applies to drugs the plan covers, so a missing drug is not protected by it.

If the yearly total is still hard to carry, the Medicare Prescription Payment Plan spreads it across monthly bills; Medicare.gov is clear that it does not lower the total. If your income is low, drugmaker free-medicine programmes may cover the drug instead.

Step 4: if it is not covered, how an exception works

A formulary exception asks the plan to cover a drug it does not list, or to lift a restriction. Medicare.gov's appeals page says your prescriber must provide a statement explaining the medical reason the exception should be approved, and the request is expedited when waiting "may seriously jeopardize your life, health, or ability to regain maximum function." Under 42 CFR 423.568 and 423.572 the plan must decide within 72 hours of receiving the prescriber's supporting statement, or 24 hours for an expedited request.

Medicine, strength and form: ____________________
Plans compared (name and plan ID): ____________________

For each plan:
[ ] Is the exact product on the 2027 formulary?
[ ] Tier: ___   Prior authorization? Y/N   Step therapy? Y/N   Quantity limit? ______
[ ] Specialty pharmacy required? Which one? ______
[ ] Deductible (max $700 in 2027): $____   Coinsurance or copay: ______
[ ] Out-of-pocket cap if covered: $2,400 for 2027

If no plan lists it:
[ ] Ask the prescriber now for a supporting statement for a formulary exception
[ ] Note the plan's exception phone/fax and the 72-hour (24-hour fast) clock
[ ] New to the plan? Ask for the transition supply in the first 90 days
[ ] Ask the drug's manufacturer support line about bridge or free-drug help
[ ] NORD RareCare: 1-800-999-6673

What if the plan denies it after you enroll?

A denial after enrollment starts a five-level appeal ladder, and each level has its own deadline. At Level 1 you, your representative or your prescriber ask the plan for a redetermination within 65 days; the plan decides a benefits appeal in 7 days, a payment appeal in 14 days, or a fast appeal in 72 hours. Each later level must be requested within 60 days of the previous decision.

Rare-disease help outside the plan

Help from outside the plan can bridge a gap while an exception or appeal runs. NORD (the National Organization for Rare Disorders) runs RareCare patient assistance programmes that it says offer "medication assistance, insurance premium and co-pay support, and emergency relief" for eligible patients, reachable at 1-800-999-6673. Manufacturer hubs are the other route: Novartis's Fabhalta and Vanrafia programmes each publish a free bridge of up to 12 months for privately insured patients whose coverage is delayed or denied, though not for Medicare patients, who are pointed to the Novartis Patient Assistance Foundation instead. Compare every drugmaker's free-medicine income limit in our 2026 income limits table.

What should you do, by situation?

• If you are new to Medicare and take a rare-disease drugRun the drug through every Part D or Medicare Advantage plan in your area before December 7; in the 2026 data most plans did not list the newest kidney medicines, so the plan choice matters more than the premium.
• If no plan in your area lists your drugPick the plan whose pharmacy network and exception process fit you best, get the prescriber's supporting statement ready for January, and use the 90-day transition supply as the bridge.
• If you buy through the MarketplaceCheck the drug on each insurer's 2027 list and choose by December 15 so coverage starts January 1; a manufacturer copay card can then apply because Marketplace plans are commercial insurance.
• If you are already on the drug and your plan is dropping itThe formulary-change rules require notice; switch during open enrollment if another plan lists it, or request an exception to keep it.

Related: the general open enrollment drug checklist, Marketplace drug coverage 2027 and the prior authorization guide.

Frequently asked questions

The bottom line

For a rare-disease medicine the formulary, not the premium, decides the year: in 2026 most Part D plans did not list the newest kidney and complement drugs. Run the four checks before December 7 (or December 15 for the Marketplace), and if no plan lists your drug, have the prescriber statement ready so the 72-hour exception clock starts on January 1.

Sources

1. Medicare.gov. Joining a plan (open enrollment dates). medicare.gov checked 2026-10-19
2. Medicare.gov. Costs for Medicare drug coverage ($700 deductible, $2,400 cap in 2027). medicare.gov checked 2026-10-19
3. Medicare.gov. Appeals in Medicare drug plans. medicare.gov checked 2026-10-19
4. HealthCare.gov. Dates and deadlines for 2027 health insurance. healthcare.gov checked 2026-10-19
5. eCFR. 42 CFR 423.568, standard coverage determination timeframes. ecfr.gov checked 2026-10-19
6. eCFR. 42 CFR 423.572, expedited coverage determination timeframes. ecfr.gov checked 2026-10-19
7. eCFR. 42 CFR 423.120, transition process. ecfr.gov checked 2026-10-19
8. Centers for Medicare & Medicaid Services. Part D formulary file, contract year 2026 (September 2026). data.cms.gov (zip) checked 2026-10-04
9. NORD. RareCare patient assistance programs. rarediseases.org checked 2026-10-19
10. Novartis. FABHALTA Co-Pay Plus and Bridge Program (C3G). fabhalta.com checked 2026-10-19