Medicare Part D

Does Your Drug Plan Ride With Original Medicare or Not?

LONGMONT, Colo. — If you take even one prescription, the way you get Medicare drug coverage matters. For 2027, there are still two main ways to get it: a stand-alone Part D plan that pairs with Original Medicare, or a Medicare Advantage plan that has drug coverage built in. They can look similar at the pharmacy counter, but the plumbing behind them is different — and moving from one to the other changes more than just your ID card.

Medicare Part DLongmont, CO

Here is a plain-language look at how the two structures compare, and what actually changes if you switch between them.

The two structures, side by side

With Original Medicare plus a stand-alone Part D plan, you have two separate pieces. Original Medicare (Parts A and B) covers hospital and doctor services directly through the federal program. A private Part D plan, which you choose and pay for separately, handles your prescriptions. Many people also add a Medigap policy to help with Original Medicare's cost-sharing.

With a Medicare Advantage plan that includes drug coverage (often called an MAPD), one private plan covers your Part A, Part B, and Part D benefits together. You still have Medicare, but the plan administers your benefits, usually through a network of doctors and hospitals.

Longmont is in Boulder County, where residents can choose from plans in both categories. Availability, networks, and formularies are set at the county level, so two people living a few miles apart in different counties may see different options.

What stays the same in 2027

Some Part D rules apply no matter which path you take:

• The out-of-pocket cap for covered drugs is $2,100 in 2026 and $2,400 in 2027. Once your spending on covered prescriptions hits that ceiling, you pay nothing for the rest of the year on those drugs.
• The maximum Part D deductible is $615 in 2026 and $700 in 2027. Plans can charge less, but not more.
• The old coverage gap (“donut hole”) is gone as of 2025. Part D now has three phases: deductible, initial coverage, and catastrophic.
• The Medicare Prescription Payment Plan is available in both structures. It lets you spread your drug costs across the calendar year in monthly bills instead of paying big amounts at the pharmacy.
• IRMAA surcharges on Part B and Part D can apply if your income is above $109,000 as a single filer in 2026 (higher for joint filers). This is based on your tax return, not on which plan you pick.

What changes if you switch from Part D to a Medicare Advantage plan

Moving from stand-alone Part D to a Medicare Advantage plan is not just a drug-plan swap. You are also changing how the rest of your care is paid for.

• Your medical coverage moves. Instead of Original Medicare paying providers directly, your Medicare Advantage plan does. That usually means using the plan's network and following its rules for referrals or prior authorization.
• Your Medigap policy is affected. Medigap only works with Original Medicare. If you drop Original Medicare for Medicare Advantage, your Medigap policy no longer pays anything, and in most cases you would end it.
• Your drug list may look different. Every plan has its own formulary — the list of covered drugs and the tier each one falls into. A medication that was on a low tier in your old plan might sit on a higher tier in the new one.
• Your pharmacy network may change. Preferred pharmacies, mail-order options, and 90-day fill rules are set by each plan.

What changes if you switch the other direction

Going from a Medicare Advantage plan back to Original Medicare plus stand-alone Part D also has ripple effects.

• You will need to actively choose a Part D plan. Dropping an Advantage plan does not automatically give you drug coverage; a separate Part D enrollment is required to avoid gaps and the late-enrollment penalty.
• Medigap is a bigger question. Outside your one-time Medigap Open Enrollment window (the six months after you first enroll in Part B at age 65 or older), insurers in most states can use medical underwriting to decide whether to sell you a policy and at what price. Colorado has some additional protections, but the rules are detailed — this is a good moment to call your local SHIP counselor before you switch.
• Provider access can shift. Original Medicare is accepted by most doctors and hospitals nationwide that take Medicare, which is different from working inside an Advantage plan's network.

When you can actually make the change

Two main windows apply to most people:

• Annual Enrollment Period: October 15 – December 7. You can join, switch, or drop a Part D plan or a Medicare Advantage plan. Changes take effect January 1.
• Medicare Advantage Open Enrollment Period: January 1 – March 31. If you are already in a Medicare Advantage plan, you can switch to a different one or return to Original Medicare (and add a stand-alone Part D plan). This window is not for people currently on Original Medicare.

Special Enrollment Periods can also open a door outside these windows — for example, after a move, or if your plan leaves the area.