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Standalone Part D premiums are going down on average in 2026, which is not the direction most Medicare costs move. CMS projects the average total premium for a standalone prescription drug plan at $34.50 a month in 2026, down from $38.31 in 2025. The average hides a wide spread. In many states you can find basic plans under $10 a month and enhanced plans above $80, and the cheapest premium is frequently the most expensive plan once your actual prescriptions are priced in.
Part D is where Medicare shopping gets personal, because the right plan depends on your medication list. This guide covers the premium, the deductible, the $2,100 out-of-pocket cap that now defines the program, and the extra amounts higher-income enrollees pay.
The premium, and the benchmark behind it
CMS calculates a national base beneficiary premium each year. For 2026 it is $38.99 a month. You will not see that exact figure on any plan’s price tag, because each insurer bids its own premium around it. The base premium still matters to you for two reasons. It is the number Medicare uses to calculate your late enrollment penalty if you went without drug coverage, and it anchors the income-related surcharge described below.
Premiums also stayed lower than expected because of a federal premium stabilization program that paid insurers to limit increases while the redesigned Part D benefit settled in. CMS has announced that program ends after 2026, and early projections for 2027 point to higher standalone premiums. If your plan’s price jumps next fall, that policy change is a large part of the reason. Our deeper look at Medicare Part D in 2026 covers deductibles, drug tiers, and the cap mechanics.
The deductible and the $2,100 cap
For 2026, no Part D plan can set a deductible above $615. Some plans set it lower, and some apply the deductible only to higher drug tiers, so two plans with similar premiums can treat your first prescriptions of the year very differently. After the deductible, you pay copays or coinsurance set by the plan’s tiers until your total out-of-pocket spending on covered drugs reaches $2,100. From that point, you pay $0 for covered drugs for the rest of the year.
The cap replaced the old coverage gap, and it changed the math for anyone on an expensive brand-name or specialty drug. Before the redesign, a single specialty medication could produce five figures of cost sharing across a year. Now the worst case for covered drugs is known in advance: your premiums, plus up to $615 of deductible spending, plus tier cost sharing up to the $2,100 ceiling. Medicare also offers a payment program that spreads your drug costs evenly across the year instead of bunching them into the first months, which helps if hitting the deductible in January strains your budget.
The IRMAA surcharge on Part D
If your 2024 modified adjusted gross income was above $109,000 as a single filer or $218,000 filing jointly, Social Security adds an income-related amount to your Part D premium. For 2026 the surcharge runs from $14.50 a month in the first bracket to $91.00 a month in the top bracket. It is charged on top of whatever your plan premium is, and it follows you from plan to plan, so switching to a cheaper plan does not remove it. The full bracket table sits in our guide to Medicare IRMAA surcharges in 2026, along with how to appeal if your income has dropped.
Why the lowest premium often loses
Plans sort drugs into tiers, and the same medication can sit on tier 2 in one plan and tier 3 with prior authorization in another. A $6 plan that puts your main prescription on a 33% coinsurance tier will cost you more by March than a $40 plan that covers it for a $45 copay. Pharmacies matter too. Plans negotiate prices with pharmacy networks, and the same prescription at the same plan can cost noticeably more at a non-preferred pharmacy.
The only reliable comparison is to enter your exact medication list, dosages, and pharmacy into the Medicare Plan Finder during open enrollment and compare the estimated total yearly cost it produces for each plan. That figure combines premium, deductible, and expected copays. It takes fifteen minutes and it routinely differs by hundreds of dollars between plans whose premiums look similar.
Help with Part D costs
Extra Help, the federal low-income subsidy for Part D, pays part or all of the premium, the deductible, and much of the cost sharing for people with limited income and resources. Anyone enrolled in a Medicare Savings Program gets Extra Help automatically. Our guide to Medicare Savings Programs in 2026 covers those income limits. State pharmaceutical assistance programs add another layer in some states.
One more warning belongs in every Part D discussion. Going without creditable drug coverage after you are first eligible starts a penalty clock that adds about 1% of the base premium for every uncovered month, permanently. Sixty-three days is the grace window. Our guide to Medicare late enrollment penalties shows what that adds up to if you delay for a year or more.
