For years, people called Medicare’s Part D coverage gap the “donut hole”: after you and your plan spent past an initial coverage limit, you paid a much higher share of drug costs until you hit catastrophic coverage. Policy changes—especially under the Inflation Reduction Act path—have been shrinking and redesigning that gap. By 2026, Part D’s out-of-pocket structure is meant to look less like the old hole and more like a capped yearly drug spend, with manufacturer and plan liability shifting in ways that matter when you compare plan finders on Medicare.gov.
This guide is a consumer map, not a substitute for the official Medicare & You handbook. Drug coverage basics: What is prescription drug coverage. Advantage plan medical OOP caps are a different bucket: Medicare Advantage MOOP basics. Medigap does not generally fill Part D the way it fills Parts A/B gaps: What is Medigap.
Old gap vs redesigned shape (plain English)
| Era / idea | What shoppers felt at the pharmacy | What to verify for your year |
|---|---|---|
| Classic “donut hole” | After initial coverage, you paid a large % of negotiated price until catastrophic | Historical context only for older EOBs |
| Closing / discount years | Brand/generic discounts inside the gap reduced the shock but did not erase stages | Read the Explanation of Benefits stage labels |
| 2025–2026 redesign path | Lower / redesigned out-of-pocket maximum for Part D covered drugs; fewer “surprise gap” months for many specialty users | Confirm the plan year you are in on Medicare.gov and your Annual Notice of Change |
Exact dollar caps, TruOOP (true out-of-pocket) definitions, and manufacturer discount mechanics change by year. Treat any blog number as stale until you match it to CMS materials for the enrollment year you are shopping.
What still drives your bill inside Part D
- Formulary and tier — preferred generics vs specialty coinsurance (Formulary exception when a drug is non-formulary).
- Deductible — some plans still have a Part D deductible before copays kick in.
- Pharmacy network — preferred mail order (Express Scripts, OptumRx, CVS Caremark channels) vs retail.
- IRMAA — higher-income surcharges are separate from the donut-hole story; they change your premium, not the stage chart alone.
- Medicare Advantage vs standalone PDP — drug stages live in Part D either way; medical MOOP does not pay your Rx coinsurance.
Named anchors in this space include CMS, Medicare.gov Plan Finder, Social Security (for IRMAA), and major Part D / MA-PD sponsors such as UnitedHealthcare, Humana, CVS/Aetna, and Kaiser Permanente plan menus—always compare the specific contract ID, not the parent brand alone.
Worked example: specialty fill across stages
Morgan takes a specialty oral drug with a $1,200/month negotiated price. In an older gap-heavy year, Morgan’s EOB might show months of low copays, then several months of hundreds of dollars in the coverage gap, then catastrophic coinsurance. Under a redesigned year with a lower annual Part D OOP cap (illustrative—confirm 2026 CMS figures), Morgan’s planner goal shifts from “will I fall in the hole in August?” to “when do I hit the yearly Rx OOP maximum, and which plan’s deductible + tiers get me there with less cash up front?”
Morgan compares two PDPs on Medicare.gov: Plan A has a $0 Rx deductible but specialty coinsurance of 30%; Plan B has a modest deductible and a preferred specialty tier copay. Morgan lists every NDC, runs Plan Finder, and prints the estimated annual cost—not just the premium. For non-Medicare drug math on an employer plan, the same formulary discipline in Prescription drug coverage still applies.
Shopping moves that still matter
- Use Medicare.gov Plan Finder with your full drug list every Open Enrollment.
- Read the Annual Notice of Change—gap/OOP redesigns show up as new stage charts.
- Ask the pharmacist which stage the claim adjudicated to on the receipt/EOB (Medical bills and insurance).
- Do not assume Medigap or Advantage MOOP covers Part D patient share.
- Manufacturer copay cards often cannot be used with federal programs the way they work on commercial insurance—verify.
Checklist
- Confirm which calendar year rules apply to the card in your wallet.
- Enter every drug and pharmacy into Plan Finder before you renew on autopilot.
- Note deductible, tiers, and estimated total annual drug cost—not premium alone.
- Watch AOBs/EOBs for stage labels so a spike is not a mystery.
- Separate IRMAA premium questions from coverage-gap questions.
- Re-check specialty prior auth before a January 1 plan switch.
Part D IRMAA surcharges are separate from coverage-gap cost-sharing: Medicare IRMAA basics.
CMS star ratings for MA-PD and PDP contracts when you compare drug plans: Medicare Advantage star ratings basics.
Educational only. Not Medicare counseling, insurance, or medical advice. Part D parameters change by statute and CMS guidance; verify figures in current Medicare publications and your plan documents.