Medicare Supplement Plans in Seattle, Washington: What to Know for 2027

In Seattle, Washington, Medigap is the route many people take to make their Medicare costs predictable. This 2027 guide lays out the standardized plans, what each helps pay, and your enrollment rights in King County, in straightforward language.

Here's the Seattle picture in plain terms. Your county sets your Medicare options, and Seattle sits in King County (part of Seattle area) — so that's the lens for everything below.

59 Medicare Advantage plans are available for 2027. Roughly 54% of people with Medicare in the county have chosen Medicare Advantage over Original Medicare, among the roughly 320,899 residents who are 65 or older. Those are factual, area-level counts — we don't rank plans.

Expect the companies active locally, a jargon-free walkthrough of how Medicare works, the 2027 costs, the enrollment calendar, and free help when you want a person to talk to.

What Medigap does — and doesn't — cover

Think of Medigap as the layer that sits on top of Original Medicare to absorb the costs it leaves you: the deductibles, the 20% coinsurance, the copays that otherwise have no annual ceiling.

The catch that trips people up is that these plans are federally standardized — a Plan G from one insurer covers exactly what a Plan G from another does. So the letter defines the benefits, and price and service are what separate companies. Medigap doesn't include drug coverage, so most people in Seattle, Washington pair it with a stand-alone Part D plan.

Below we break down what each standardized plan covers and the enrollment rights that matter most in Seattle, Washington. It's a framework, not a ranking — and we don't quote premiums.

What Medicare costs in 2027

It helps to separate the costs everyone shares from the costs that vary by plan. The program-level numbers here are set nationally — the same whether you're in a big city or a rural county.

Part B premium. Most people pay the standard Part B premium of $202.90 a month in 2026 (2026 amount; 2027 figure will be posted when CMS releases it). Part A is premium-free for most people who worked and paid Medicare taxes long enough.

Part D drug costs. In 2027, a Part D plan's yearly deductible can be no more than $700, and a $2,400 cap limits what you pay out of pocket for covered prescriptions across the year — a real change for anyone with high drug costs.

Higher earners pay more for Parts B and D through an income-related adjustment called IRMAA, which for 2026 starts above $109,000 in annual income for an individual and is based on your 2024 tax return. Most people fall below that line and pay the standard amounts. The 2027 brackets will be posted when CMS releases them.

Plan-specific costs. What an individual plan charges — its premium, deductible, copays, and what it covers — varies by plan and changes yearly. We don't publish those figures or rank plans; Medicare's Plan Finder shows the current details for your situation, and a licensed agent can walk you through them.

When you can enroll or make changes

Medicare's enrollment windows are federal — the same nationwide — so the timing below applies wherever you live.

Your first window (IEP). When you're new to Medicare, your Initial Enrollment Period is the 7-month window around your 65th birthday month. Signing up on time helps you avoid late penalties that can follow you for years.

Annual Enrollment Period (AEP). Each fall, from October 15 – December 7, anyone with Medicare can join, switch, or drop a Medicare Advantage or Part D plan. Changes take effect January 1.

Medicare Advantage Open Enrollment. From January 1 – March 31, if you're already in an Advantage plan you get one chance to switch plans or return to Original Medicare.

Special Enrollment Periods can also open after certain life events, like moving or losing other coverage. The interactive calendar further down lays the year out visually.

Where to get free, unbiased help near Seattle

Good Medicare help exists and it's free — you don't have to figure this out solo or pay for guidance.

For official specifics and the Plan Finder tool, go straight to Medicare.gov or 1-800-MEDICARE (TTY 1-877-486-2048). And a licensed agent can compare options and handle the paperwork with you.

One note on who we are: MyMedicarePlans.org is an independent, privately owned educational resource — not Medicare, not a government agency, and not affiliated with one. Our job is to help you get oriented, then hand you off to the official sources and licensed professionals for plan decisions.

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