Part D prescription coverage, explained.

Medicare Part D is the prescription drug benefit you buy from a private insurer to go alongside Original Medicare. It is optional, but if you go without it (or without other drug coverage that counts as creditable) after you first become eligible, you pay a late enrollment penalty that gets added to your premium permanently. In 2026 that penalty is 1% of the $38.99 national base premium for every month you went uncovered, and it follows you for life. The single most important thing to know is that plans are not interchangeable: the same medication can sit on a cheap tier in one plan and an expensive tier in another in your own zip code, so you compare plans by entering your actual drug list, not by chasing the lowest monthly premium. This page is educational. Apex Health Advisors is not connected with or endorsed by the U.S. government or the federal Medicare program. To compare and enroll in Part D plans, use the Plan Finder at Medicare.gov or call 1-800-MEDICARE.

What Part D actually is, and who needs it

Original Medicare (Parts A and B) does not cover most prescriptions you fill at a pharmacy. Part D is the separate piece that does. It is sold by private insurers, you choose it, and you pay a monthly premium on top of your Part B premium. If you have a Medicare Advantage plan instead, drug coverage is usually built in, so a stand-alone Part D plan is mostly for people on Original Medicare or a Medigap policy.

Here is the trap I have watched people walk into for years. Someone turns 65, takes nothing but a daily vitamin, and decides Part D is a waste of money. Three years later they get a diagnosis, suddenly need a brand-name drug, and now they are paying for the plan plus a permanent penalty at the same time. Part D is insurance against the prescriptions you don't have yet.

The late enrollment penalty, with the real math

The penalty is 1% of the national base beneficiary premium for each full month you could have had Part D (or other creditable drug coverage) and didn't. In 2026 that base is $38.99. The penalty is calculated against the base, not your plan's premium, it rounds to the nearest dime, and it is added to your premium for as long as you have Part D. It also moves a little each year as the base premium changes.

Say you waited three years after becoming eligible before signing up. That is 36 uncovered months, so 36% of $38.99, which works out to roughly $14 added to your premium every single month, for life. Not a one-time fee. A permanent surcharge that quietly costs you thousands over a Medicare retirement.

Creditable coverage and the 63-day clock

You can skip Part D without a penalty if you already have drug coverage that is at least as good as standard Part D. That is called creditable coverage, and employer plans, retiree plans, TRICARE, VA benefits, and FEHB often qualify. The catch is that your insurer has to tell you each year whether your coverage is still creditable, usually in a notice before October 15. Keep those notices. You may need to prove it later.

One thing to watch heading into 2026: the way creditable status gets tested has changed, and some employer and retiree drug plans that counted in past years may not count now. So do not assume. If you lose creditable coverage, you have 63 days to pick up Part D before the penalty starts running. Missing that window is the most common way people who knew better still got hit.

Why two plans with the same premium can cost wildly different amounts

Every Part D plan has a formulary, which is its list of covered drugs sorted into tiers. Most plans use five or six: preferred generics at the bottom (cheapest), then generics, preferred brands, non-preferred drugs, and specialty drugs at the top. Tier placement is set by each plan, not by Medicare. A medication that sits on Tier 2 in one plan can land on Tier 4 in another plan sold in the same zip code, and your copay follows the tier.

That is why the cheapest monthly premium is so often a bad deal. A $0-premium plan can cost you far more over a year if it parks your specific drugs on high tiers, puts your pharmacy out of its preferred network, or slaps prior authorization or step therapy on something you take daily. You compare on estimated annual total cost, not the sticker premium.

What changed for 2026

The benefit has been reworked over the last two years, and a lot of older advice is now wrong. The coverage gap, the old donut hole, was eliminated permanently in 2025. There is now a hard out-of-pocket cap of $2,100 for 2026: once your covered-drug spending hits it, the plan pays 100% for the rest of the year. The deductible can be no higher than $615, and many plans charge less.

• If you face a big cost early in the year, the Medicare Prescription Payment Plan lets you spread your out-of-pocket spending across the remaining months of the plan year instead of paying it all at once.
• Federal price negotiation took effect on January 1, 2026 on ten widely used drugs, including Eliquis, Jardiance, and Xarelto. If you take one of these, your cost may be lower than in past years depending on your plan.
• Extra Help (the Low Income Subsidy) caps copays at $12.65 for brand drugs and $5.10 for generics for those who qualify. Eligibility is based on both income and resources, so the income figure alone does not tell the whole story. A lot of people who qualify never check, so check.

How to actually compare plans

Do not eyeball this from a brochure. Go to the Plan Finder at Medicare.gov, enter every drug you take by name and dosage, add your pharmacy, and let it show you the estimated annual total cost (premium plus deductible plus copays) for each plan side by side. That number is what matters, and it is the only honest way to see which plan is cheapest for you specifically.

This page is educational only and we are not naming or recommending specific plans here. Apex Health Advisors is not connected with or endorsed by the U.S. government or the federal Medicare program. To compare and enroll, use Medicare.gov or call 1-800-MEDICARE (1-800-633-4227), TTY 1-877-486-2048, 24 hours a day, 7 days a week.

Educational information only. Apex Health Advisors is not connected with or endorsed by the U.S. government or the federal Medicare program. We do not offer or promote specific Medicare Advantage or Part D plans on this page. To compare and enroll in Part D plans, use the Plan Finder at Medicare.gov or call 1-800-MEDICARE (1-800-633-4227), TTY 1-877-486-2048, 24 hours a day, 7 days a week.