Choosing a Medicare Drug Plan Under the Part D Spending Cap

For 2026, nobody with a Medicare drug plan pays more than $2,100 out of pocket for covered drugs. That single cap has flipped the old way of choosing a plan. For a retiree on several expensive brand drugs, the plan with the lowest premium is now often the cheapest overall, as long as it covers every drug they take.

This piece explains how the cap works, then walks through comparing plans on your own prescriptions. If you are still choosing between Original Medicare with a drug plan and a Medicare Advantage plan that includes drugs, start with Medicare Advantage vs Original Medicare. The rest of Medicare's structure is in how Medicare works.

What the annual cap does and when it applies

Since 2025, Part D has had a hard yearly limit on out-of-pocket spending for covered drugs. For 2026 it is $2,100. What counts toward it: your deductible, copays and coinsurance for drugs on your plan's formulary, plus some payments made on your behalf by programs such as Extra Help. What does not count: your monthly premium, and anything you pay for a drug the plan does not cover.

Once you reach $2,100, you pay nothing more for covered drugs until January. The old coverage gap, the "donut hole", no longer exists in the standard benefit. The Medicare page on what drug coverage costs sets out the 2026 benefit, including the maximum deductible a plan can charge, $615 for 2026.

Premium, deductible and the tiers

Every plan sets four things that decide what you pay:

• Premium: the monthly charge, whether or not you fill a prescription.
• Deductible: what you pay before the plan starts sharing costs, up to $615 in 2026. Some plans charge none, or exclude cheap generics from it.
• Tiers: groups of drugs with different copays or coinsurance, from preferred generics at the bottom to specialty drugs at the top.
• Formulary: the list of drugs the plan covers. Each plan's list is different.

Before the cap, a high-premium plan with low copays could save heavy users money. Now that every plan stops at $2,100, a heavy user pays the same $2,100 in any plan that covers their drugs, and the premium becomes the main difference.

Three plans for the same retiree, worked

A retiree takes three brand-name drugs and two generics. At the plans' negotiated prices, the five drugs cost about $1,000 a month in total, $12,000 a year, before any plan pays. Three illustrative plans in the same area:

With $12,000 of drug costs, every plan's cost sharing reaches the $2,100 cap during the year, so out-of-pocket is identical. Plan A wins by $432 over Plan B and $876 over Plan C, on premiums alone. Plan B's $0 deductible and Plan C's low copays only change how quickly the retiree reaches the cap, not where they end up.

The same plans if one drug is off the formulary

Now suppose Plan A does not cover one of the brand drugs, which costs $400 a month. The retiree pays full price for it, and none of that counts toward the cap.

• Plan A: $144 premiums + $2,100 capped costs on the four covered drugs + $4,800 for the uncovered drug = $7,044.
• Plan B, which covers all five: $2,676.

The cheapest plan became the most expensive by more than $4,000. Formulary coverage is the first test, before price.

And for a light user

A retiree whose only prescriptions are two generics costing $20 a month in total pays $240 a year in drug costs. Under Plan A they pay $144 in premiums plus up to $240, since the deductible covers all of it: $384. Under Plan B, $576 plus small copays. Plan A still wins, but for a different reason: the light user never comes near the cap.

Running your drug list through the plan finder

The Medicare Plan Finder does this comparison for every plan in your ZIP code. It asks for:

1. every drug, with its strength, form and the quantity you take each month
2. the pharmacies you use, since a plan's preferred pharmacies can charge lower copays
3. whether you get Extra Help

Sort the results by estimated total drug and premium cost for the year. Then, for the top three, open the plan details and check each drug for coverage restrictions:

• Prior authorization: your doctor must get approval before the plan pays.
• Step therapy: you must try a cheaper drug first.
• Quantity limits: a cap on how much the plan pays for each fill.

A drug that technically appears on the formulary but needs approval your doctor cannot get is, in practice, not covered. Ask your doctor's office which restrictions they deal with easily.

The payment plan that spreads costs across the year

Even with the cap, a retiree on expensive drugs can face most of the $2,100 in January and February, as the deductible and coinsurance stack up on the first fills. The Medicare Prescription Payment Plan, available in every Part D and Medicare Advantage drug plan, lets you pay those costs in monthly installments instead of at the pharmacy counter.

Signed up from January, $2,100 becomes roughly $175 a month. It does not reduce the total and carries no interest. It is worth it for anyone who would otherwise struggle with a large bill early in the year, and pointless for someone with small drug costs. You opt in through your plan, and you can do it before the year starts.

Reviewing every fall

Plans change their premiums, deductibles and formularies every January. Your plan must send an Annual Notice of Change by the end of September. Read it for three things: has the premium changed, has any of your drugs moved tiers or left the formulary, and has the deductible changed.

Then rerun the Plan Finder during open enrollment, October 15 to December 7, even if you plan to stay. It takes under an hour, and a single drug moving off a formulary can change the answer by thousands of dollars. If you also have a Medigap policy, that is a separate decision with different rules, covered in Medigap Plan G vs Plan N.

When this does not apply

If you qualify for Extra Help. People with limited income and assets can get help with premiums, deductibles and copays through the Low-Income Subsidy, which changes which plans are cheapest. Apply through Social Security.

If you have creditable drug coverage from an employer or retiree plan. You may not need Part D at all. Check the plan's yearly creditable coverage notice before dropping it, because rejoining it later may be impossible.

If you are in a Medicare Advantage plan with drug coverage. You choose drug coverage as part of the whole plan. The same cap applies, but you cannot pair Advantage medical coverage with a separate drug plan in most cases.

If you are deciding when to sign up, not which plan. Missing your first chance to enroll without other creditable coverage brings a late penalty for life. The timing rules come before plan choice.

Next steps

1. List every prescription with dose and monthly quantity.
2. Run the list through the Medicare Plan Finder between October 15 and December 7.
3. Sort by total yearly cost and confirm every drug is on the formulary of the plans you shortlist.
4. Check restrictions on each drug with your doctor's office.
5. If your costs are high, opt in to the Medicare Prescription Payment Plan before January.