Medicare Part D Cost Calculator
Your drugs a month, and what your plan charges for them
Your result will appear here
Fill in the fields on the left and this updates as you type.
Know what this estimate is based on
- Jurisdiction
- General mathematical model
- Scope and limitations
- Educational estimate only. Confirm the assumptions, current rules, fees, and rounding that apply to your situation before making a decision.
- Source links checked
- Jul 30, 2026
Built and regression-tested by Smart Tools Lab. It has not been individually reviewed by a licensed financial, tax, or legal professional.
How to use
- 01
Enter what your prescriptions cost a month at the pharmacy's full price, before insurance pays anything. Generics and brand-name drugs go on separate lines because plans charge for them differently. The example on this page uses $60 of generics and $800 of brand-name drugs, $860 a month in all.
- 02
Enter what your plan charges once the deductible is met: a flat copay for the generics, $12 a month in the example, and your share of the brand-name price, 25% here, which is the share the 2026 defined standard benefit uses.
- 03
Enter your plan's yearly deductible and its monthly premium. The 2026 maximum deductible is $615, but many plans charge less and some charge nothing, so use the figure from your own plan's summary of benefits rather than the maximum.
- 04
Read the headline, which is what Part D costs you across the whole year, then the month you reach the $2,100 out-of-pocket cap. After that month, covered prescriptions cost you nothing until January.
- 05
Set the payment plan field to 1 to see the year billed as monthly instalments instead of paid at the counter. The last column of the table shows those bills in either case, so you can compare them against what you would pay at the pharmacy before deciding.
Formula
The 2026 defined standard benefit runs in three phases across a calendar year. Phase 1, the deductible: you pay 100% of the price of your drugs until you have paid the plan's deductible, which can be no more than $615 in 2026. Phase 2, initial coverage: you pay your plan's cost sharing on everything after that — a flat copay for generics, or a percentage of the price for brand-name drugs, 25% under the defined standard. Phase 3, the cap: once your true out-of-pocket costs reach $2,100, you pay nothing more for covered drugs until the next calendar year. True out-of-pocket costs = the deductible you paid + copays + coinsurance on covered drugs. Premiums are excluded. This page spreads your monthly drug cost evenly across twelve months. Within a month where the deductible runs out, it splits the deductible between generic and brand drugs in proportion to what each costs, then applies the copay and the coinsurance to whatever is left. Medicare Prescription Payment Plan, as medicare.gov calculates it: the January bill is the lesser of what you owe that month and the out-of-pocket cap divided by 12. In every later month the bill is (the balance you still owe + that month's new costs) divided by the number of months left in the year. The yearly total is identical either way.
Example
A retiree takes one generic costing $60 a month and one brand-name drug costing $800 a month, $860 in all at the pharmacy's full price, which is $10,320 over a year. Their plan charges the maximum $615 deductible, $12 a month in generic copays, 25% of the brand-name price and a $40 monthly premium. January is the expensive month: the $615 deductible comes out first, and the part of the month's drugs left after it adds $60.40, so January costs $675.40. From February to July the deductible is finished and each month costs $212.00 — the $12 generic copay plus 25% of $800. By the end of July they have paid $1,947.40. August needs only $152.60 to reach the $2,100 cap, and from September to December covered prescriptions cost nothing at all. The year comes to $2,580: $2,100 for drugs and $480 in premiums. Without the cap the same prescriptions would have cost $3,007 in cost sharing, so the cap is worth $907. The most expensive single month is $675.40. Run again with the Medicare Prescription Payment Plan switched on, the same year is billed as $175.00 in January, $64.76 in February, rising through $136.02 in May to $232.16 for each month from August to December. The total is still $2,100 — the option moves the money through the year without reducing it.
Definitions
- Deductible
- The amount you pay for covered drugs at full price before the plan starts paying its share. In 2026 a Part D plan may charge up to $615, and many charge less or nothing (CMS).
- Initial coverage phase
- The stretch after the deductible and before the out-of-pocket cap, where you pay your plan's copay or coinsurance on each prescription. Under the 2026 defined standard benefit that share is 25%.
- True out-of-pocket costs (TrOOP)
- The running total that counts toward the $2,100 cap: the deductible, copays and coinsurance you pay for covered drugs. Premiums and non-covered drugs are excluded.
- Out-of-pocket cap
- The yearly ceiling on what you pay for covered Part D drugs, $2,100 in 2026 and $2,000 in 2025. Once you reach it, covered prescriptions cost you nothing for the rest of the calendar year.
- Medicare Prescription Payment Plan
- A free option, offered by every Part D plan, that spreads your out-of-pocket drug costs across the calendar year as monthly bills from the plan instead of payments at the pharmacy. It does not lower the total.
Good to know
The three phases the Inflation Reduction Act left behind
For most of Part D's history the benefit had four phases, and the third was notorious. After a deductible and a stretch of ordinary cost sharing, a beneficiary fell into the coverage gap — the donut hole — where they paid a far larger share of every prescription. Beyond that lay catastrophic coverage, which sounded like protection but was not: it charged 5% of the price of each drug with no ceiling at all. For someone taking a drug costing thousands a month, 5% of an unlimited amount was itself an unlimited amount, and there was no year in which the bills stopped. The Inflation Reduction Act rebuilt the benefit around a hard ceiling. From 2025 the coverage gap and the catastrophic coinsurance are both gone, and what remains is three phases. First the deductible, which a plan may set anywhere up to $615 in 2026 and which you pay at the full price of your drugs. Then the initial coverage phase, where you pay your plan's cost sharing — 25% of the price under the defined standard benefit, while the plan pays 65% or 75% and the manufacturer contributes a 10% discount on brand-name drugs. Then the cap: once what you have paid for covered drugs reaches $2,100, you pay nothing more for them until January. This page's example shows how quickly that runs. A retiree taking $60 of generics and $800 of brand-name drugs a month pays $675.40 in January, because the $615 deductible lands first. February through July each cost $212.00, which is a $12 generic copay plus 25% of $800. By the end of July they have paid $1,947.40, so August needs only $152.60 to reach the ceiling, and September through December cost nothing. The whole year's cost sharing is $2,100 against drugs worth $10,320 at full price. The ceiling is what makes a year like that plannable, and it is the single largest change to Medicare drug coverage in twenty years.
What counts toward the cap, and what quietly does not
The $2,100 ceiling is precise about what it measures, and the gap between that and what leaves your bank account surprises people. The official name for the running total is true out-of-pocket costs, usually shortened to TrOOP, and it counts what you actually pay for covered drugs: the deductible, flat copays and percentage coinsurance. It does not count your plan premium. In the example the premium is $40 a month, which adds $480 across the year, and not one cent of it moves the total toward the ceiling. That is why the page reports $2,580 as the cost of the year but only $2,100 against the cap. If you reach the ceiling in August, as the example does, your premium still arrives every month through December. The second exclusion matters more and is easier to miss: drugs your plan does not cover at all. Every Part D plan publishes a formulary, the list of drugs it covers, arranged in tiers that set the cost sharing for each. A drug that is not on that list is not a covered Part D drug, so what you pay for it does no work toward the cap. Neither does what you spend at a pharmacy outside your plan's network, and neither do over-the-counter medicines. The practical consequence is that two people spending the same amount at the pharmacy can reach the ceiling months apart, purely because of which drugs are on which list. Manufacturer discounts are the counter-intuitive case: the 10% discount a manufacturer applies to a brand-name drug in the initial coverage phase does count toward your total even though you did not pay it, which is a rule left over from the old coverage gap. Before assuming a drug will carry you to the cap, check it against your plan's formulary. If it is not there, the plan's appeals process — or a switch at the next open enrolment — is the route, and the cap is not protecting you in the meantime.
The Medicare Prescription Payment Plan, and who it actually helps
The redesign left one problem unsolved. A hard ceiling is a good thing, but reaching it quickly means paying a great deal in a short time, and the deductible guarantees that January is the worst month of the year. The Medicare Prescription Payment Plan is the answer to that timing problem and nothing else. Every Part D plan must offer it, it is free to join, and you can start in any month. Once you opt in, the pharmacy charges you nothing when you collect a prescription; the plan pays the pharmacy in full and then bills you monthly. Medicare is unusually blunt about the limits of the option, saying that it 'doesn't save you money or lower your drug costs'. The arithmetic bears that out. Medicare's published examples set the first month's bill at the lesser of what you owe and the out-of-pocket maximum divided by twelve, which in 2026 is $175. Every month after that is billed as the balance you still owe plus that month's new costs, divided by the number of months left in the year. Applied to this page's example, January falls from $675.40 at the counter to a $175.00 bill, February is $64.76, May is $136.02, and each month from August to December is $232.16. The total across the year is $2,100 — exactly what it would have been without the option. What has changed is the shape, not the size. That makes the plan genuinely useful for someone whose costs land early and whose income arrives evenly, which describes most people on a fixed monthly benefit. It is much less useful for someone whose drug costs are low or spread thinly, because they will end the year paying the same amount in more instalments, having added a bill to keep track of. There is also a real risk attached: these are bills, and failing to pay them can end your participation for the rest of the year. Anyone whose costs are high because their income is low should look at Extra Help first, because that programme lowers the total rather than rearranging it.
Choosing a drug plan when the ceiling is the same everywhere
The $2,100 cap is set in law, so it is identical in every Part D plan sold in the United States. That sounds as though it removes the reason to compare plans, and it does the opposite: because the worst case is now fixed, the differences between plans show up entirely in how fast you reach it and what you pay along the way. Four things vary and all of them are worth checking. The deductible is the first. The 2026 maximum is $615, and a plan may charge less or nothing at all; a plan with no deductible spreads your costs more evenly through the year, which changes the month you reach the ceiling even when the yearly total is similar. The premium is the second, and it is the figure most people compare because it is the easiest to find. It deserves less weight than it usually gets: in the example the premiums come to $480 across the year against $2,100 of drug costs, so a plan that is $10 a month cheaper but charges more for your particular drugs is a poor trade. The formulary is the third and by far the most important. A plan that does not cover one of your drugs leaves you paying for it with money that does not count toward the cap, which is the worst outcome available. Check every drug you actually take, by name and dose, against the plan's list before comparing anything else. The pharmacy network is the fourth: many plans set lower cost sharing at preferred pharmacies, and using one outside the network can mean no coverage at all. All four change every year. Plans revise their formularies, premiums and deductibles each autumn, and a plan that suited you this year may not next year, so the annual open enrolment window is worth using even when nothing about your health has changed. Comparing plans against the exact list of drugs you take, by name and dose, rather than on premium alone, is the only reliable way to run this comparison, and medicare.gov is the place to do it.
Frequently asked questions
How much will my prescriptions cost under Part D in 2026?
It depends on the price of your drugs and what your plan charges, but the cap makes the worst case knowable. On this page's example — $60 of generics and $800 of brand-name drugs a month, a $615 deductible, $12 of generic copays and 25% of the brand price — the year costs $2,580: $2,100 for the drugs themselves and $480 in plan premiums. Those drugs cost $10,320 a year at full price, so the plan absorbs most of it.
What is the $2,100 out-of-pocket cap?
It is the most you can pay in 2026 for covered drugs under any Part D plan. Once your deductible, copays and coinsurance for covered drugs add up to $2,100, you pay nothing for them for the rest of the calendar year. CMS set the figure in the Final CY 2026 Part D Redesign Program Instructions; it was $2,000 in 2025 and the law indexes it each year, so expect it to keep rising.
When during the year will I reach the cap?
In the example, in August. The year starts expensive because the deductible comes first: January costs $675.40, then each month from February to July costs $212.00, and August costs $152.60 — just enough to reach $2,100. September through December cost nothing at the pharmacy. Spending is rarely that even in real life, and a big fill early in the year pulls that month forward.
Does the Medicare Prescription Payment Plan save me money?
No. Medicare states plainly that it 'doesn't save you money or lower your drug costs'. It spreads what you owe across the calendar year instead. In the example the January pharmacy bill of $675.40 becomes a $175.00 plan bill, the largest monthly bill is $232.16, and the yearly total is $2,100 either way. It helps with cash flow when costs land early, which a deductible guarantees they will.
Do my plan premiums count toward the cap?
No, and this catches people out. The cap counts only what you pay for the drugs themselves — the deductible, copays and coinsurance on covered prescriptions. The $40 a month premium in the example adds $480 over the year and none of it counts, which is why the page shows $2,580 in total but only $2,100 against the cap. Drugs your plan does not cover at all do not count either.
What happened to the coverage gap, or donut hole?
It is gone. The Inflation Reduction Act redesigned the benefit, and from 2025 there are three phases instead of four: the deductible, an initial coverage phase where you pay a share of each prescription, and then nothing once you reach the out-of-pocket threshold. The old coverage gap and the 5% catastrophic coinsurance that never stopped were both removed, which is what makes a hard ceiling possible.
What if I cannot afford my share even with the cap?
Check Extra Help, Medicare's low-income subsidy for drug costs, before anything else. It lowers premiums, the deductible and cost sharing for people who qualify, so it changes these figures rather than trimming them. Qualifying for Medicaid, a Medicare Savings Program or Supplemental Security Income qualifies you automatically; otherwise you apply through Social Security. The income and resource limits are set by the agency, so ask Social Security or 1-800-MEDICARE rather than assuming you earn too much.