Medicare Part D is not free. It’s the part of Medicare that covers prescription drugs, and it comes with a monthly premium, an annual deductible, and cost-sharing when you fill prescriptions. That said, your actual costs vary widely depending on which plan you choose, your income, and whether you qualify for financial assistance. Some people end up paying very little or nothing at all.
What Part D Typically Costs
Part D is offered through private insurance companies approved by Medicare, so there’s no single price. Every plan sets its own monthly premium, and these can range from under $10 to over $100 per month depending on the plan and where you live. On top of the premium, most plans charge an annual deductible before coverage kicks in. For 2025, the maximum allowable deductible is $590, though many plans set theirs lower or waive it entirely for certain drugs.
Once you’ve met the deductible, you typically pay 25% of your drug costs (coinsurance) until you hit the annual out-of-pocket cap. Starting in 2025, that cap is $2,000 per year, a major change brought by the Inflation Reduction Act. After reaching $2,000 in out-of-pocket spending, you pay nothing for covered drugs for the rest of the calendar year.
This $2,000 cap replaced the old “donut hole” system, where people with high drug costs faced a coverage gap that left them paying a larger share. The coverage gap phase has been eliminated entirely as of 2025, which is a significant cost reduction for anyone taking expensive medications.
When Part D Can Be Free or Nearly Free
Medicare’s Extra Help program (also called the Low-Income Subsidy) can eliminate or drastically reduce your Part D premiums, deductibles, and copays. If you qualify for full Extra Help, you may pay nothing for your drug plan. For 2026, the income limits are $23,940 for an individual and $32,460 for a married couple. Your countable resources (savings, investments, but not your home or car) must also fall below $18,090 for an individual or $36,100 for a couple.
If your income or resources are slightly above those thresholds, you may still qualify for partial Extra Help, which reduces your costs without eliminating them completely. Medicaid recipients and people who get Supplemental Security Income automatically qualify.
Zero-Premium Medicare Advantage Plans
Some Medicare Advantage plans (Part C) advertise $0 premiums and include drug coverage bundled in. This can make it look like Part D is free, but there are important caveats. You still pay your Part B premium every month, which is $185 or more in 2025. And $0-premium Advantage plans often have narrower pharmacy networks, formulary restrictions, or higher copays at the pharmacy counter. The premium is just one piece of the total cost picture.
Most Medicare Advantage HMO and PPO plans include drug coverage automatically. If yours does, you cannot also join a separate standalone Part D plan. If your Advantage plan doesn’t include drug coverage (rare, but it happens with certain plan types like Medical Savings Account plans), you can enroll in a standalone Part D plan separately.
Higher Earners Pay a Surcharge
If your income is above certain thresholds, you’ll pay an extra monthly amount on top of your plan’s standard premium. This surcharge is called IRMAA (Income-Related Monthly Adjustment Amount), and it’s based on your tax return from two years prior.
For single filers, the surcharge starts when income exceeds $109,000. For married couples filing jointly, it kicks in above $218,000. The extra charge ranges from $14.50 to $91.00 per month depending on how high your income is. At the top bracket (single filers earning $500,000 or more, or joint filers at $750,000 or more), you’d pay an additional $91 per month on top of whatever your plan already charges.
The Penalty for Not Enrolling on Time
One cost that catches people off guard is the late enrollment penalty. If you don’t sign up for Part D when you’re first eligible and go 63 days or more without creditable drug coverage (coverage that’s at least as good as Part D), you’ll pay a permanent surcharge when you do eventually enroll.
The penalty adds 1% of the national base beneficiary premium for every month you went without coverage. The base premium for 2026 is $38.99, so each uncovered month adds roughly $0.39 to your monthly bill, and that penalty stays with you for as long as you have Part D. Someone who waited three years to enroll would face a penalty of about $14 per month, every month, indefinitely. Even if you’re healthy and don’t take medications now, this penalty is a strong reason to enroll during your initial eligibility window.
How to Lower Your Part D Costs
Your biggest lever is plan selection. During open enrollment each fall (October 15 through December 7), you can compare plans on Medicare.gov using your specific medications. Plans vary dramatically in which drugs they cover, what tier those drugs fall on, and what your copay will be. A plan with a higher monthly premium might save you money overall if it covers your medications at a lower copay.
Many Part D plans also offer a Medicare Prescription Payment Plan starting in 2025, which lets you spread your out-of-pocket drug costs across the year in monthly installments rather than paying large amounts upfront at the pharmacy. This doesn’t reduce your total costs, but it can make them more manageable month to month.
If your income is limited, applying for Extra Help through Social Security is the single most impactful step. You can apply online at ssa.gov, by phone, or at your local Social Security office. The application is straightforward, and approval can save you thousands of dollars a year on medications.