Medicare 2026

Before you pick a Medicare plan, pick a structure

Mercer Island, Washington — When you become eligible for Medicare, one of the biggest decisions you'll make isn't which plan to pick. It's which structure to use. You can stay with Original Medicare and add a Medigap policy (and usually a separate Part D drug plan), or you can get your coverage through a Medicare Advantage plan. These two paths work very differently, and understanding how they're built makes everything else easier to sort out.

How Original Medicare is put together

Original Medicare is the traditional, federally run program. It has two main parts: Part A (hospital insurance) and Part B (medical insurance, like doctor visits and outpatient care). You can go to any doctor, hospital, or specialist in the country that accepts Medicare, and you don't need referrals.

But Original Medicare on its own doesn't cover everything. It has deductibles, coinsurance, and no annual out-of-pocket cap. That's where two add-ons come in:

• Medigap (also called Medicare Supplement) is private insurance that helps pay some of the costs Original Medicare leaves behind, like the 20% coinsurance on Part B services.
• Part D is a standalone prescription drug plan you buy from a private insurer.

Put together, Original Medicare + Medigap + Part D is a three-piece setup. You pay separate premiums for each piece, but the trade-off is broad provider access and more predictable out-of-pocket costs.

How Medicare Advantage is put together

Medicare Advantage (Part C) is different. Instead of coverage coming directly from the federal government, you get your Part A, Part B, and usually Part D benefits bundled into a single plan run by a private insurance company that contracts with Medicare.

Advantage plans typically use provider networks — HMOs, PPOs, and similar structures — so which doctors and hospitals you can see (and at what cost) depends on the plan. Many Advantage plans also include extras that Original Medicare doesn't cover, like routine dental, vision, or hearing benefits. Costs, rules, and networks vary from plan to plan.

The key structural point: with Advantage, one plan handles almost everything. With Original Medicare + Medigap, you're assembling the pieces yourself.

What's available around Mercer Island

Mercer Island is in King County, where residents have a large number of Medicare Advantage plans and Part D plans to choose from during enrollment periods. Availability is set at the county level, so your ZIP code determines the exact menu. You can see the current list on Medicare's Plan Finder at medicare.gov.

Whether you go with Original Medicare + Medigap or Medicare Advantage, the core Medicare rules — like Part D's out-of-pocket cap ($2,100 in 2026, $2,400 in 2027) and maximum deductible ($615 in 2026, $700 in 2027) — apply the same way.

Questions that usually drive the decision

A few practical questions tend to shape which path fits:

• Do you want to see any provider nationwide, or is a local network fine? Original Medicare with Medigap offers the widest access. Advantage plans usually focus on local networks.
• How do you feel about monthly premiums vs. costs when you use care? Medigap generally means higher monthly premiums but fewer surprises when you get care. Advantage plans often have lower premiums but copays and coinsurance as you use services, up to the plan's annual limit.
• Do you travel or split time between states? That can weigh in favor of Original Medicare's nationwide access.
• Do you take specific prescriptions? Check that your drugs are covered under whichever Part D setup you're considering — either standalone or built into an Advantage plan.

Important dates to know

Two windows matter most:

• Annual Enrollment Period: October 15 – December 7. You can join, switch, or drop a Medicare Advantage or Part D plan.
• Medicare Advantage Open Enrollment Period: January 1 – March 31. If you're already in an Advantage plan, you can switch to another Advantage plan or return to Original Medicare (and pick up a Part D plan).

One thing worth knowing: Medigap has its own enrollment rules. In most states, you have a one-time six-month guaranteed-issue window when you first enroll in Part B at age 65 or older. Outside that window, insurers may be able to use medical underwriting, which can affect whether you can get a Medigap policy later. Washington has some state-specific rules on Medigap; check with Washington's SHIBA program (the state's SHIP) for details.

A quick note on Part D in 2027

Whichever path you choose, prescription drug coverage now works the same way. The coverage gap — the old "donut hole" — was eliminated in 2025, and Part D now has three phases: deductible, initial coverage, and catastrophic. In 2027, once your out-of-pocket spending on covered drugs hits $2,400, you pay nothing more for covered drugs the rest of the year. You can also ask to spread your drug costs across the year through the Medicare Prescription Payment Plan.

Higher-income enrollees may pay an IRMAA surcharge on Part B and Part D premiums; in 2026, those surcharges start above $109,000 in income for single filers.