GlossaryMay 15, 2026·2 min read·By Jacob Posner, Founder & Editor

What Is Medicare Part D?

Medicare Part D covers prescription drugs through private plans approved by CMS. In 2026, the annual out-of-pocket cap is $2,100, insulin costs no more than $35/month, and all recommended vaccines are $0.

Quick Answer: Medicare Part D is the prescription drug benefit available since 2006 to anyone enrolled in Medicare. Plans are offered as standalone Prescription Drug Plans (PDPs) or bundled into Medicare Advantage. The Inflation Reduction Act capped 2026 out-of-pocket drug costs at $2,100 and set a $35/month limit on insulin. Low-income enrollees may qualify for Extra Help, a federal subsidy that reduces or eliminates premiums and cost-sharing.

Annual Medicare Part D Limits

Current annual limits
Feature2026 AmountNotes
Out-of-pocket cap$2,100After cap: $0 cost-sharing (catastrophic)
Insulin (any covered brand)$35/month maxIRA cap, effective 2023
Recommended vaccines$0Shingles, flu, COVID-19, others
Avg monthly premium~$40-55/monthVaries by plan; higher earners pay IRMAA surcharge

Source: CMS Medicare Part D 2026 parameters (cms.gov). IRMAA surcharges apply above $106,000 individual income.

Source: https://www.cms.gov/medicare/prescription-drug-coverage/prescriptiondrugcovgenin

Standalone PDP vs. Medicare Advantage Drug Coverage

Part D comes in two forms. A standalone Prescription Drug Plan (PDP) pairs with Original Medicare (Parts A and B). Medicare Advantage plans (Part C) typically bundle drug coverage, so you don't need a separate PDP. You cannot hold both at the same time. Each plan has its own formulary: a tiered list from generic (Tier 1) to specialty (Tier 5), with cost-sharing rising at higher tiers. Formularies change annually; review your plan's Annual Notice of Change each fall before the Medicare Annual Enrollment Period. If you are comparing plans, does Medicare cover prescription drugs explains what Part D actually covers and where gaps remain. Low-income enrollees may qualify for Extra Help, which can nearly eliminate Part D cost-sharing.

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Frequently Asked Questions

What is the 2026 Medicare Part D out-of-pocket cap?

$2,100 in 2026. Once your total out-of-pocket drug spending hits that threshold, you enter catastrophic coverage and pay $0 for the rest of the plan year. This cap was created by the Inflation Reduction Act and 2026 threshold is $2,100, up from $2,000 in 2025. See the CMS 2026 parameters at cms.gov for details. If a drug bill looks wrong, use the medical bill analyzer to check it.

What is the late enrollment penalty for Part D?

1% of the national base beneficiary premium for each full month you went without Part D or other creditable drug coverage after becoming eligible. The penalty is permanent. Creditable coverage from an employer or union plan avoids it entirely; keep the annual creditable coverage notice your plan sends each fall.

Who qualifies for Extra Help with Part D costs?

Extra Help (the Low Income Subsidy) is a federal program for Medicare enrollees with limited income and resources. In 2026, eligibility generally requires income at or below about 150% of the federal poverty level. Extra Help reduces or eliminates Part D premiums, deductibles, and copays. Apply at ssa.gov.

You may qualify for free health insurance.

Our 2-minute screener checks Medicaid, ACA, Medicare, CHIP, and more. Most uninsured Americans qualify for $0/month coverage they didn't know about.

Check what I qualify for — free

Sources & References

  1. 1. CMS: Medicare Part D Prescription Drug Coverage — Official CMS page for Part D parameters including 2026 OOP cap and formulary requirements.
  2. 2. Medicare.gov: Drug Coverage (Part D) — Official Medicare.gov resource explaining Part D enrollment, plans, and costs in 2026.
  3. 3. KFF: Medicare Part D Premiums Decreasing for Many Stand-Alone Drug Plans in 2026 — KFF analysis of 2026 Part D plan availability, average premiums, and IRA impact.
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