Medicare Part D

Medicare's New $2,100 Drug Cap Starts in 2026: What Miles City Should Know

MILES CITY, Mont. — Starting Jan. 1, 2026, Medicare Part D will cap what you pay out of pocket for covered prescription drugs at $2,100 for the year. Once you hit that number, you pay $0 for the rest of 2026 on covered medications at the pharmacy. For older adults in Custer County who have watched drug prices climb, this is one of the most meaningful changes Medicare has made in years — and it's worth understanding before the Annual Enrollment Period closes on Dec. 7.

A big change is coming to your pharmacy counter

The cap is a program-wide rule set by the Centers for Medicare & Medicaid Services (CMS). It applies whether your drug coverage comes through a stand-alone Part D plan or is built into a Medicare Advantage plan.

What the $2,100 cap actually covers

The cap counts what you spend out of pocket on covered Part D drugs — your deductible, copays, and coinsurance. In 2026, the maximum Part D deductible a plan can charge is $615, though plans can set it lower.

A few things the cap does not cover:

• Your monthly Part D premium.
• Drugs that aren't on your plan's formulary (its covered drug list).
• Medications given in a doctor's office or hospital, which usually fall under Part B.

If you take even one high-cost specialty medication, you could reach the $2,100 ceiling early in the year — and then pay nothing more for covered prescriptions until January.

The "donut hole" is gone

For years, Part D had a confusing middle phase called the coverage gap, or "donut hole," where your share of drug costs jumped once you and your plan had spent a certain amount together. That gap was eliminated as of 2025.

Now there are just three phases:

1. Deductible phase — you pay full negotiated price until you meet your plan's deductible (up to $615 in 2026). 2. Initial coverage phase — you pay copays or coinsurance until your out-of-pocket total reaches $2,100. 3. Catastrophic phase — you pay $0 for covered drugs the rest of the year.

Simpler math, fewer surprises.

The Medicare Prescription Payment Plan: spreading the cost out

Even with the cap, $2,100 in January is still $2,100. That's where the Medicare Prescription Payment Plan comes in.

This is an optional program — sometimes called "M3P" or drug cost smoothing — that lets you pay your out-of-pocket drug costs in monthly installments across the calendar year instead of all at once at the pharmacy. You don't pay more overall, and there's no interest or fee. Your plan bills you monthly; you still pick up your prescriptions as usual.

Who tends to benefit most? People who take expensive medications early in the year, or anyone on a fixed monthly budget who would rather not face a large pharmacy bill in a single month.

To join, you opt in through your Part D or Medicare Advantage drug plan. You can sign up before the plan year begins or at any point during the year.

What this means locally

Miles City is in Custer County, where Medicare beneficiaries choose from stand-alone Part D drug plans as well as Medicare Advantage plans that include drug coverage. The $2,100 cap, the $615 maximum deductible, and the payment-plan option apply to all of them — those are federal rules, not plan features.

That said, plans still differ on premiums, formularies, pharmacy networks, and which tier your specific drugs fall into. Two plans following the same federal rules can still leave you with very different bills. It's worth checking that your medications are covered and that your preferred Miles City pharmacy is in-network before you lock in a choice.

Deadlines to keep on your calendar

• Oct. 15 – Dec. 7, 2025: Medicare Annual Enrollment Period. This is when you can join, switch, or drop a Part D or Medicare Advantage plan for 2026.
• Jan. 1 – March 31, 2026: Medicare Advantage Open Enrollment. If you're already in a Medicare Advantage plan, you get one chance to switch to another or return to Original Medicare.

One more note: if your income was above $109,000 (single filer) on your most recent tax return, you may owe an IRMAA surcharge on top of your Part D premium in 2026. Social Security notifies you if this applies.