Medicare Part D Plan Comparison Calculator
Drug plan cost from medication list and dosages.
About this calculator
This calculator walks a beneficiary's annual drug spending through the two-phase Medicare Part D benefit design created by the Inflation Reduction Act, effective 2025-01-01: a deductible phase, then 25% coinsurance (or a small nominal cost-share for Low-Income Subsidy/Extra Help recipients) on remaining drug costs until the beneficiary's own out-of-pocket spending reaches a hard annual cap, after which the plan covers 100% of remaining drug costs for the rest of the year. The pre-2025 benefit design -- a coverage gap ("donut hole") phase and 5% catastrophic coinsurance triggered by an $8,000 true-out-of-pocket threshold -- was eliminated by the IRA and no longer exists; this calculator models the current law, not the benefit design many beneficiaries may remember from before 2025. Low-income subsidy recipients skip the deductible phase entirely and pay a nominal cost-share well below the standard 25% coinsurance rate, which is why that toggle produces the largest single swing in the results for anyone who qualifies.
Annual drug cost drives the total for most enrollees below the annual cap, since it is the base the deductible-then-coinsurance calculation runs on -- though once spending is high enough to reach the cap, the total stops responding to further drug costs at all, and for someone flagged low-income-subsidy eligible, the monthly premium plus any IRMAA surcharge can matter more to the total than drug spending itself. Two inputs are collected for context but do not change the total either way under the standard (non-LIS) coinsurance rate: the brand-name drug percentage and the medication count are not used in the underlying phase calculation, since standard Part D coinsurance applies the same percentage to brand and generic drugs alike. What it does not account for: plan-specific formularies, tier-based copays that many real plans use instead of flat coinsurance, the exact CMS-published LIS copay schedule (modeled here as an illustrative flat rate), or mid-year formulary changes.
Medical Disclaimer
This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about your health. Never disregard professional medical advice or delay seeking it because of results from this tool.
Inputs
Results
Total Annual Cost
$1,631.00
Figures current as of 2026. Source: CMS Fact Sheet: Final CY 2026 Part D Redesign Program Instructions
How to Use This Calculator
- Enter monthly plan premium ($) and annual drug costs ($) for each plan being compared.
- Set brand-name drug percentage and number of medications (context only under standard coinsurance -- see the FAQ).
- Enter IRMAA surcharge tier if income exceeds Medicare thresholds.
- Toggle Low-Income Subsidy (Extra Help) on if the beneficiary qualifies -- it waives the deductible and replaces standard coinsurance with a small nominal cost-share.
- Review total annual cost including premiums and out-of-pocket costs, which are capped once out-of-pocket spending reaches the annual limit under the post-2025 benefit design.
- Compare plans during Open Enrollment (Oct 15 - Dec 7) each year -- best plan changes as formularies change.
How the result changes with Annual Drug Costs ($)
| Annual Drug Costs ($) | Total Annual Cost |
|---|---|
| 1,500 | $1,256.00 |
| 2,250 | $1,444.00 |
| 4,500 | $2,006.00 |
| 7,500 | $2,520.00 |
What each input means
- Monthly Plan Premium ($)
- Monthly premium for the Part D plan. National average ~$33/mo.
- Annual Drug Costs ($)
- Total retail cost of all your prescriptions per year.
- Brand-Name Drug %
- Percentage of your drugs that are brand-name (vs generic).
- Number of Medications
- Total number of different prescriptions you take.
- IRMAA Surcharge Tier
- Income-related surcharge: 0 = none (income <$103k), 1-4 = higher income tiers.
- Low-Income Subsidy (Extra Help)
- 1 = Eligible for Extra Help/LIS, 0 = Not eligible.
What each result means
- Total Annual Cost
- Combined premiums and out-of-pocket drug costs for the year.
- Annual Premiums (incl. IRMAA)
- Total premium payments including any IRMAA surcharge.
- Annual Out-of-Pocket
- Deductible plus coinsurance, capped at the IRA's hard annual out-of-pocket limit.
- Deductible Paid
- Amount paid toward the annual deductible ($615 in 2026).
- Plan Coverage Ratio
- Percentage of total drug costs covered by the plan.
- Cost per Med per Month
- Average monthly cost per medication after all plan benefits.
- Net Savings vs. Retail
- Total savings compared to paying full retail price (negative = plan costs more).
How this is calculated
Worked example, using the default values
- Identify Input Parameters6 parametersMonthly Plan Premium ($) = 35, Annual Drug Costs ($) = 3000, Brand-Name Drug % = 30, Number of Medications = 5 = 6 input(s) provided
- Calculate Total Annual CostTotal Annual Cost = totalPremiumCost + totalOOP1631 = $1,631
- Calculate Annual PremiumsAnnual Premiums = annualPremium + irmaaSurcharge420 = $420
- Calculate Annual Out-of-Pocket1211 = $1,211
Figures and sources
- 2026 Medicare Part D deductible (2026) — CMS Fact Sheet: Final CY 2026 Part D Redesign Program Instructions
Engine last updated . Checked against 3 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does the low-income subsidy toggle produce such a large drop in total cost?
Low-Income Subsidy (Extra Help) does two things in the calculation: it waives the deductible entirely, so none of the annual drug spend goes toward that phase, and it replaces the standard 25% coinsurance rate with a small nominal cost-share on remaining drug costs. Both effects compound, which is why this single eligibility toggle produces a bigger swing in total annual cost than changing the monthly premium or moving between IRMAA tiers.
What happens to out-of-pocket costs once the annual cap is reached?
Once the beneficiary's own out-of-pocket spending (deductible plus coinsurance payments) reaches the Inflation Reduction Act's hard annual cap, the plan covers 100% of any remaining drug costs for the rest of the year -- the beneficiary pays nothing more. This is a genuine $0 stop, not the old 5% "catastrophic coinsurance" rate that applied under the pre-2025 benefit design; that phase, and the coverage gap before it, were both eliminated effective 2025-01-01. It's also why total out-of-pocket cost isn't a straight percentage of drug cost for high spenders -- the total flattens out once the cap binds.
Does the brand-name drug percentage change the total cost estimate?
No, under the standard (non-LIS) coinsurance rate -- brand-name percentage and number of medications are collected for context but are not used in this calculator's phase-by-phase cost formula, since standard Part D coinsurance applies the same 25% rate to brand-name and generic drugs alike. Real-world plans can still differ on formulary tier placement and specific drug pricing, but the statutory coinsurance percentage this calculator models does not distinguish brand from generic.
Is this the same Medicare Part D design I remember from a few years ago?
No. Before 2025, Part D had four phases including a coverage gap ("donut hole") at 25% coinsurance and a 5% catastrophic-coinsurance phase triggered once true out-of-pocket spending crossed $8,000. The Inflation Reduction Act eliminated the coverage gap entirely and replaced the open-ended catastrophic coinsurance with a hard annual out-of-pocket cap (indexed each year; $2,000 in 2025) beyond which beneficiaries pay $0 more, effective 2025-01-01. This calculator models the current two-phase design, not the older one.
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