The Inflation Reduction Act permanently transformed Medicare prescription drug coverage. Starting in 2025 and continuing in 2026, there is a hard $2,100 annual out-of-pocket cap on covered drugs—a massive change from the old system that could leave beneficiaries paying thousands before catastrophic coverage kicked in. This guide explains how Part D works today, how to find the best plan, and little-known programs that can slash your drug costs even further.
Medicare Part D is the prescription drug benefit offered through private insurance companies that have contracts with Medicare. Unlike Part A (hospital) and Part B (medical), Part D is not provided directly by the federal government—it is administered by hundreds of private plans that must meet Medicare's minimum coverage standards.
Part D covers outpatient prescription drugs: medications you pick up at a pharmacy, not drugs administered in a hospital or doctor's office (those are typically covered under Part B). You can get Part D coverage two ways:
If you are in Original Medicare, you should enroll in a standalone Part D plan even if you do not currently take any prescription drugs. If you skip Part D and go more than 63 days without creditable drug coverage, you will owe a permanent late enrollment penalty when you do eventually sign up.
Medicare Part D plans in 2026 follow a redesigned structure established by the Inflation Reduction Act. Here is how the year typically flows for a beneficiary with standard drug costs:
Most Part D plans charge a deductible before coverage kicks in. The maximum deductible in 2026 is $590. During this phase, you pay 100% of the cost for covered drugs (at the plan's negotiated rates) until you hit your deductible. Some plans have a $0 deductible—typically for generic drugs, even if a deductible applies to brand-name drugs.
Once you have met your deductible, you move into the initial coverage phase. Here you pay your plan's copays or coinsurance for each prescription, based on the drug's tier. You remain in this phase until your total out-of-pocket spending reaches the $2,100 cap.
Before the Inflation Reduction Act, Part D had a notorious "coverage gap" or "donut hole" where, after your initial coverage phase ended, you would suddenly pay much higher cost-sharing (often 25%) until you hit a catastrophic threshold that was previously around $8,000 or more in total out-of-pocket spending.
That system is gone. In 2026, once your true out-of-pocket (TrOOP) spending reaches $2,100, you automatically enter catastrophic coverage and pay $0 for all covered drugs for the rest of the calendar year.
This is a transformational change for beneficiaries who take expensive specialty medications. Someone taking a biologic drug for rheumatoid arthritis or a cancer medication that previously cost $10,000+ per year in personal spending can now cap their exposure at $2,100 and pay nothing more for the remainder of the year.
What counts toward the $2,100 cap: Your deductible payments, your copays/coinsurance during the initial coverage phase, and manufacturer discounts on brand-name drugs (a change from prior law). What does NOT count: your monthly premiums.
The average Part D premium in 2026 is approximately $53.95 per month, according to CMS data. However, premiums vary enormously by plan and by location:
Do not choose a Part D plan based on premium alone. The plan with the lowest monthly premium may cost you far more in deductibles and copays on your specific medications than a plan with a higher premium. Always use Medicare's Plan Finder tool to compare your estimated total annual cost.
Since August 2023, Medicare Part D permanently caps the monthly cost of any covered insulin at $35 per month—regardless of which drug tier the insulin falls on and regardless of whether you have met your deductible. This applies to standalone Part D plans and Medicare Advantage drug plans.
For the approximately 3.3 million Medicare beneficiaries who use insulin, this cap has delivered significant savings. Many were previously paying $100–$400+ per month for insulin that now costs $35. The cap applies to each individual type of insulin—if you use two different types, the cap applies to each one separately (so a maximum of $70/month for two insulins).
Every Part D plan has a formulary—a list of covered drugs organized into cost tiers. Plans typically use 5 to 6 tiers, though structures vary by plan:
| Tier | Drug Type | Typical Cost-Share |
|---|---|---|
| Tier 1 | Preferred generics | $5–$15 copay |
| Tier 2 | Non-preferred generics | $15–$30 copay |
| Tier 3 | Preferred brand-name drugs | $35–$50 copay |
| Tier 4 | Non-preferred brand-name drugs | $60–$100 copay |
| Tier 5 | Specialty drugs (high-cost) | 25–33% coinsurance |
| Tier 6 | Select preferred generics | $0 (some plans) |
The tier a drug is placed on varies from plan to plan. A drug that is Tier 3 on one plan may be Tier 4 on another, doubling your out-of-pocket cost. This is why it is critical to check whether each of your specific drugs is on the formulary and at what tier before choosing a plan.
Plans can also require prior authorization before covering certain drugs, step therapy (requiring you to try a cheaper drug first), or quantity limits (limiting how many pills you can receive per fill). Check these restrictions for your medications when comparing plans.
Extra Help, also called the Low Income Subsidy (LIS), is a federal program that dramatically reduces Part D costs for beneficiaries with limited income and resources. In 2026, you may qualify if your annual income is below:
Resource limits also apply—generally $17,220 for an individual and $34,360 for a couple, not counting your home, car, or burial funds.
Extra Help benefits in 2026 include:
The average Extra Help recipient saves more than $5,300 per year on prescription drug costs. If you receive Medicaid, Medicare Savings Program benefits, or Supplemental Security Income (SSI), you are automatically enrolled in Extra Help—you do not need to apply separately. Others must apply through Social Security (ssa.gov) or their State Medicaid office.
The Medicare Plan Finder at medicare.gov is the most powerful tool for choosing a Part D plan. Here is how to use it effectively:
If your Part D plan denies coverage for a medication your doctor has prescribed, you have the right to appeal. The process has two speed options:
If the plan upholds its denial, you can escalate to an Independent Review Entity (IRE), then to an Administrative Law Judge, then to the Medicare Appeals Council. Many denials are overturned at the first or second level of appeal—do not give up after one rejection.
If you have prescription drug coverage from another source—an employer, retiree plan, or VA benefits—it must be "creditable," meaning it is as good as Medicare Part D coverage on average. Your employer or insurer must notify you each year whether your coverage is creditable. If it is not creditable and you go without joining Part D, you will owe a late enrollment penalty when you eventually do sign up. Keep any creditable coverage notices you receive—you may need them to prove you did not have a gap.