Part D Out-of-Pocket Cap and Prescription Payment Plan Calculator
Medicare caps what you pay for covered Part D drugs each year. The Medicare Prescription Payment Plan lets you spread those costs over monthly bills instead of paying at the pharmacy. See when you hit the cap, what you pay each month at the counter, and what your monthly bill would be on the plan.
Estimate your monthly costs
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| Month | Pay at the pharmacy | Bill on the payment plan |
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Uses the 2026 and 2027 Part D cap and maximum deductible from CMS and the monthly bill formula in federal rules (42 CFR 423.137). It counts only covered Part D drugs on your plan’s formulary; premiums and drugs your plan doesn’t cover don’t count toward the cap.
How the Part D out-of-pocket cap works
Since 2025, Part D has three stages: the deductible, initial coverage, and catastrophic coverage. Once what you pay for covered drugs reaches the cap ($2,100 in 2026, $2,400 in 2027), you pay $0 for covered drugs for the rest of the calendar year. The “donut hole” is gone. The cap applies to stand-alone drug plans and to the drug coverage in Medicare Advantage plans.
Your deductible, copays and coinsurance count toward the cap. So do payments from Extra Help and most charity and family help. Your monthly premium doesn’t count, and neither do drugs your plan doesn’t cover or drugs you buy outside the plan.
How the Prescription Payment Plan bills you
On the payment plan you pay $0 at the pharmacy for covered drugs, and your drug plan sends you a monthly bill instead. It doesn’t lower your total; it changes when you pay. Federal rules set the most the plan can bill you each month:
- The month you join: the yearly cap minus what you’ve already paid this year, divided by the months left in the year (counting that month). You never pay more than that month’s actual costs.
- Each month after: what you still owe from earlier months plus that month’s new costs, divided by the months left in the year.
Because the formula divides by the months left, the plan saves you the most when you join early and have a large cost early in the year. People with low or steady drug costs, and people who get Extra Help, usually gain little from it.
Joining, renewing and leaving
Every Part D plan and Medicare Advantage plan with drug coverage must offer the payment plan. Ask your plan to sign you up before the year starts or at any point during the year. If you stay in the same plan, your enrollment carries into the next year unless you opt out; if you switch plans during open enrollment, sign up again with the new plan. You can leave at any time; you still owe what’s been billed, and you pay at the pharmacy from then on. If you don’t pay a bill by the date on your plan’s reminder notice, the plan can remove you from the payment plan, and you still owe the balance.
Questions
What is the Part D out-of-pocket cap for 2027?
$2,400 for covered Part D drugs, up from $2,100 in 2026. After you reach it, you pay nothing for covered drugs for the rest of the year.
Does the Prescription Payment Plan cost anything?
No. There’s no interest and no fee. You pay the same total as you would at the pharmacy, spread over the rest of the year.
Does my premium count toward the $2,400 cap?
No. Only what you pay for covered Part D drugs counts: the deductible, copays and coinsurance. Premiums and late enrollment penalties don’t.
Why is my first bill bigger than later ones, or smaller?
The first month uses a different formula from the months after it. With a big fill early, the first bill is capped and the rest carries forward. With steady costs, each new month adds to what you owe, so the bills rise through the year.
Sources
- CMS, CY 2027 Rate Announcement (Part D deductible and out-of-pocket threshold) — cms.gov.
- 42 CFR 423.137, Medicare Prescription Payment Plan (maximum monthly cap formula) — ecfr.gov, checked October 28, 2026.
Educational estimate. Your plan’s formulary, pharmacy and drug prices set your real costs, and your plan calculates your bills. · Advertiser disclosure