Medicare Part D Prescription Drug Coverage: A Complete 2026 Guide

What Is Medicare Part D and How Does It Work?

Medicare Part D is the federal prescription drug benefit program established in 2006. Unlike Parts A and B (which are administered directly by the government), Part D is delivered through private insurance companies approved by Medicare. You choose a plan each year during the Annual Enrollment Period (October 15–December 7).

Part D plans come in two forms:

• Standalone Prescription Drug Plans (PDPs) — Pair with Original Medicare (Parts A & B). You keep your existing Medicare and add drug coverage.
• Medicare Advantage Prescription Drug Plans (MA-PDs) — Bundled plans that combine Parts A, B, and D in a single plan, often with additional benefits like dental and vision.

Every plan has a formulary — a list of covered drugs organized into tiers. Lower tiers (generics) have lower copays; higher tiers (specialty/brand) have higher costs. Plans must cover at least two drugs per therapeutic category and all drugs in six protected classes.

What Are the Four Phases of Medicare Part D Coverage?

Part D coverage has four distinct phases that determine how much you pay at the pharmacy. Understanding these phases is critical to predicting your annual drug costs. The dollar thresholds below reflect 2026 figures.

What Is the Donut Hole and Does It Still Exist in 2026?

The "donut hole" or coverage gap has been Medicare Part D's most criticized feature since 2006. It was the phase where beneficiaries who spent more than the initial coverage limit suddenly faced much higher costs — sometimes paying 100% of drug costs — until reaching the catastrophic threshold.

In 2026, the traditional donut hole is effectively eliminated for most beneficiaries. The Inflation Reduction Act introduced a hard $2,000 annual out-of-pocket cap. Once your true out-of-pocket spending hits $2,000, you pay $0 for all remaining prescriptions for the year — regardless of which coverage phase you are in.

Additionally, Medicare now offers a Medicare Prescription Payment Plan that lets you spread your out-of-pocket costs evenly across the year in monthly installments — no interest, no fees. This prevents the front-loading of costs that previously hit beneficiaries hard in January through March.

What Is Extra Help (Low-Income Subsidy) and How Do You Qualify?

Extra Help — officially called the Low-Income Subsidy (LIS) — is a federal program that pays most Part D costs for Medicare beneficiaries with limited income and resources. Approximately 13 million people qualify, but millions of eligible individuals never apply. Extra Help is worth an estimated $5,000 per year in savings.

2026 Eligibility Criteria

What Extra Help Covers

• Part D premium — Paid in full or substantially reduced
• Deductible — Eliminated ($0)
• Copays — Reduced to $0–$11.20 per prescription
• Coverage gap — No donut hole costs

How to Apply for Extra Help

1. Online: Apply at SSA.gov/medicare/part-d-extra-help
2. By phone: Call Social Security at 1-800-772-1213 (TTY: 1-800-325-0778)
3. In person: Visit your local Social Security office
4. Through your state: Apply for Medicaid — if approved, you automatically get Extra Help

When Can You Enroll in Medicare Part D?

Medicare Part D has specific enrollment windows. Missing these deadlines can result in a permanent late enrollment penalty of 1% of the national base premium per month for every month you were eligible but not enrolled.

How Can Medicare Beneficiaries Save Even More on Prescriptions?

Even with Part D coverage, you can further reduce prescription costs with these evidence-based strategies. Many Medicare beneficiaries overpay because they do not explore all available options.

• Compare Part D plans annually. Formularies and copays change every year. The plan that was cheapest last year may not be cheapest this year. Use Medicare Plan Compare during open enrollment.
• Ask about therapeutic alternatives. If your drug is on a high copay tier, ask your doctor about lower-tier alternatives in the same drug class. Switching from a Tier 3 to Tier 1 drug can save hundreds per year.
• Use preferred pharmacies. Most Part D plans have a "preferred pharmacy" network with lower copays. Using a non-preferred pharmacy can cost 2–3× more for the same drug.
• Compare cash prices vs Part D copays. For some generics, the cash price at competing pharmacies is lower than your Part D copay. Compare pharmacy prices on Script Unlock — paying cash does not count toward your deductible, but can save money on inexpensive generics.
• Switch to 90-day mail order. Most Part D plans offer 90-day mail-order fills at a reduced copay compared to three separate 30-day fills.
• Check for manufacturer programs. Some manufacturers offer separate Medicare-specific assistance programs (distinct from standard PAPs).

How Did the Inflation Reduction Act Change Medicare Part D?

The Inflation Reduction Act of 2022 (IRA) made the most significant changes to Medicare Part D since the program launched in 2006. These changes rolled out in phases from 2023 to 2026, with the most impactful provisions now in effect.

• $2,000 out-of-pocket cap (2025+): Annual Part D out-of-pocket spending is capped at $2,000. After reaching $2,000, you pay $0 for all remaining prescriptions that year.
• $35 insulin cap (2023+): Insulin costs are capped at $35 per month per prescription for all Part D enrollees.
• Free vaccines (2023+): All Part D-covered vaccines are now $0 cost-sharing (previously some had copays).
• Medicare drug price negotiation (2026+): Medicare can now negotiate prices on the most expensive Part D drugs. The first 10 negotiated drugs take effect in 2026, including Eliquis, Jardiance, Xarelto, and Januvia.
• Inflation rebates (2023+): Manufacturers must pay rebates if they raise drug prices faster than inflation. This limits annual price increases for Part D drugs.
• Monthly payment plan (2025+): Beneficiaries can spread out-of-pocket costs in equal monthly installments throughout the year, interest-free.

Frequently Asked Questions About Medicare Part D