Medicare Advantage vs Medigap in Washington: How the Two Paths Differ
$9,850. That's the most any Medicare Advantage plan can make you pay out of pocket for in-network Part A and Part B services in 2027, under the limit CMS sets. Original Medicare on its own has no yearly limit at all. Medigap exists largely to fill that gap. Almost every other difference between the two paths follows from how each one handles that risk.
Open Enrollment runs from October 15 to December 7, 2026, and the Washington Office of the Insurance Commissioner reminded people on October 14 that this is the window to move from Original Medicare to Medicare Advantage, or back. Going one direction is simple. Going the other way can mean answering health questions to get a Medigap policy, depending on your situation. So it pays to understand the structures before you pick one.
Below is how the two set-ups work. It doesn't rank them: which fits depends on your doctors, your health, where you spend the year and how you'd handle a bad medical year.
Two paths, one Medicare
Medicare's own handbook puts it plainly: there are two main ways to get Medicare (Medicare & You 2027).
Original Medicare is Part A (hospital) and Part B (medical), run by the federal government. You can add a separate Part D drug plan, and you can buy a Medicare Supplement Insurance (Medigap) policy from a private insurer to cover much of the cost sharing Original Medicare leaves you with. Medigap plans sold after 2005 don't include drug coverage, so in practice this path is three pieces: Original Medicare, a Medigap policy and a Part D plan.
Medicare Advantage (Part C) is a Medicare-approved plan from a private company that bundles Part A, Part B and usually Part D into one plan. You still have Medicare, but you get most of your Part A and B coverage through the plan and show the plan's card instead of your red, white and blue one. Original Medicare still pays for hospice care, kidney transplant costs and some clinical research costs.
You can't combine them. It's illegal for anyone to sell you a Medigap policy while you're in a Medicare Advantage plan unless you're switching back to Original Medicare, and Medigap can't pay Medicare Advantage copays or deductibles.
| Original Medicare + Medigap + Part D | Medicare Advantage (Part C) | |
|---|---|---|
| Doctors and hospitals | Any provider that takes Medicare, anywhere in the U.S. | Usually the plan's network and service area for non-emergency care. Some plans cover out-of-network care at a higher cost |
| Specialist referrals | Not needed in most cases | May be needed (in most HMOs, yes) |
| Prior authorization | Not needed in most cases | May be needed for certain services, supplies or drugs |
| Yearly out-of-pocket limit | None in Original Medicare itself; Medigap covers much of the gap | Yes, set by each plan, no higher than $9,850 in-network in 2027 |
| Drug coverage | Separate Part D plan | Included in most plans |
| Monthly premiums | Part B premium + Medigap premium + Part D premium | Part B premium + the plan's premium, if it has one |
| Dental, vision, hearing | Mostly not covered by Original Medicare or Medigap | Many plans offer some extra benefits, usually limited |
| Care outside the U.S. | Generally not covered by Medicare; several Medigap letters cover emergencies abroad | Generally not covered; some plans offer an extra benefit |
Source: CMS, Medicare & You 2027 (pp. 10-12, 65-72, 81); Medicare.gov, How Medigap works; out-of-pocket limit from KFF.
What you pay either way
A common misunderstanding: joining Medicare Advantage doesn't stop the Part B premium. CMS's handbook says it directly. In Medicare Advantage you pay the monthly Part B premium and may also pay the plan's premium. On the Original Medicare path you pay the Part B premium, the Medigap premium and the Part D premium. The Part B premium is the one cost both paths share.
Source: CMS, 2026 Medicare Parts A & B premiums and deductibles; KFF and KFF (May 2026) for the Medicare Advantage limits.
CMS hadn't published the 2027 Part B premium as of October 17, 2026. It usually comes out in the fall, and I track it in the Part B premium 2027 post. Some Medicare Advantage plans help pay part of the Part B premium; that's a plan feature, so check it on the plan's own Summary of Benefits rather than assuming it.
The out-of-pocket structure
Here is the core trade in plain terms.
Original Medicare alone leaves you with the Part A deductible for each hospital benefit period, the Part B deductible, and usually 20% of the Medicare-approved amount for Part B services, with no annual ceiling. KFF notes Congress did pass an out-of-pocket cap for Medicare in 1988 and repealed it a year later. A Medigap policy picks up most or all of that cost sharing in exchange for a monthly premium, and with most letters your costs become fairly predictable.
Medicare Advantage sets its own copays and coinsurance for each service, so you pay as you use care, up to the plan's yearly limit. CMS caps that limit. For 2027, no plan's in-network limit can exceed $9,850, and for plans that cover out-of-network care (usually PPOs), the combined in- and out-of-network limit can't exceed $14,800 (KFF). Plans can set lower limits, and many do. That limit covers Part A and Part B services. It doesn't cover Part D drugs, which have their own cap: $2,100 in 2026 and $2,400 in 2027 on either path (CMS).
Two Medigap letters, K and L, are built more like Medicare Advantage on cost: they pay a share of most costs and have a federal out-of-pocket limit, which CMS adjusts every year.
- 2026
- 2027
Source: KFF and KFF (Medicare Advantage limits set by CMS); Medicare.gov (2026 K/L) and CMS, K & L limits for 2027
Show the numbers
| 2026 | 2027 | |
|---|---|---|
| MA in-network | $9,250 | $9,850 |
| MA in + out of network | $13,900 | $14,800 |
| Medigap Plan K | $8,000 | $8,360 |
| Medigap Plan L | $4,000 | $4,180 |
What a specific policy or plan charges is something to compare on the Medicare.gov Plan Finder or with SHIBA, not something I list here.
A worked example with 2026 numbers
| Cost sharing | Original Medicare alone | With Medigap Plan G | With Medicare Advantage |
|---|---|---|---|
| Part A hospital deductible | $1,736 | $0 (Plan G pays it) | Plan's own hospital copays |
| Part B deductible | $283 | $283 | Plan's own copays and coinsurance |
| 20% of the remaining $29,717 | $5,943.40 | $0 (Plan G pays it) | Plan's own copays and coinsurance |
| Total you pay | $7,962.40 | $283 | Depends on the plan; in-network capped at the plan's limit, no more than $9,250 in 2026 |
Source: calculated from CMS 2026 Part A and B amounts; standardized Plan G benefits from CMS, Choosing a Medigap Policy (2026); Medicare Advantage limit from KFF. Hypothetical figures.
The math: $1,736 + $283 + 20% × ($30,000 − $283) = $7,962.40 on Original Medicare alone, and it keeps climbing with each further bill. Plan G leaves the $283 Part B deductible. In Medicare Advantage, the answer sits in the plan's Evidence of Coverage, but federal rules set the ceiling.
So the real comparison is a known monthly Medigap premium with small bills afterward, versus bills that depend on how much care you use, up to a cap. They suit different people and budgets.
Networks, referrals and prior authorization
With Original Medicare, and therefore with Medigap, you can see any doctor or hospital in the U.S. that accepts Medicare. In most cases you don't need a referral to see a specialist, and you generally don't need approval in advance. A Medigap policy pays after Medicare pays, with no network of its own (Medicare SELECT policies are the exception: they use a hospital network).
Medicare Advantage plans manage care, and the rules depend on the plan type:
- HMO: you generally must use the plan's network, except for emergencies, urgent care when you're out of the area, and temporary out-of-area dialysis. In most cases you choose a primary care doctor and need a referral for specialists. Non-emergency out-of-network care without authorization can mean paying the full cost.
- PPO: you have a network, but you can also see out-of-network providers for covered services, usually at a higher cost.
- Networks change. Providers can leave a plan's network mid-year, and you generally can't change plans because of it.
Prior authorization is where the two paths feel most different day to day. Federal rules limit how Medicare Advantage plans can use it:
| Rule | What it says | Regulation |
|---|---|---|
| Purpose | Prior authorization may only be used to confirm a diagnosis or other medical criteria, or to make sure a service is medically necessary | 42 CFR 422.138(b) |
| No take-backs | Once a plan approves a service in advance, it can't later deny it as not medically necessary, except for good cause or fraud | 42 CFR 422.138(c) |
| Same coverage rules | Plans must follow Medicare's national coverage determinations and Traditional Medicare's coverage criteria | 42 CFR 422.101(b) |
| Standard decision | 7 calendar days for items subject to prior authorization (since January 1, 2026); extensions of up to 14 days are allowed in limited cases | 42 CFR 422.568(b) |
| Fast decision | 72 hours when your health requires it (24 hours for Part B drugs) | 42 CFR 422.572 |
| New members | At least 90 days without disruption or reauthorization for an active course of treatment, even with an out-of-network provider | 42 CFR 422.112(b)(8) |
| Emergencies | Covered in or out of network, with no prior authorization | 42 CFR 422.113(b) |
Source: Code of Federal Regulations, 42 CFR part 422, via eCFR (current as of October 17, 2026); Medicare & You 2027, pp. 66-72.
If a plan denies something, it must tell you in writing, and you can appeal. For anyone in the middle of treatment, such as chemotherapy or a planned surgery, the 90-day transition rule is worth knowing before a January 1 switch, and so is confirming that your current specialists are in the new plan's network.
Travel and time out of state
Original Medicare works anywhere in the U.S., including the territories. That matters if you winter in Arizona or split time between Bellingham and family in another state.
Medicare Advantage plans are built around a service area. Emergency and urgently needed care is covered in or out of the plan's network (42 CFR 422.113), but routine care away from home depends on the plan: an HMO usually won't cover a non-emergency visit with a doctor in Phoenix, while a PPO may, at its out-of-network rate. Moving out of the service area ends your eligibility for that plan and opens a special enrollment period.
Outside the U.S., neither Original Medicare nor most Medicare Advantage plans generally pay. Medigap Plans C, D, F, G, M and N cover 80% of medically necessary emergency care abroad, for care that starts in the first 60 days of a trip, after a $250 yearly deductible and up to a $50,000 lifetime maximum (WAC 284-66-064). Some Medicare Advantage plans offer a foreign travel emergency benefit as an extra. If you're a snowbird, the Medicare for snowbirds post goes deeper on two-state living.
The switching calendar
This is where the two paths are least symmetrical. You can join a Medicare Advantage plan with a pre-existing condition. Medigap is different: outside your protected windows, an insurer can ask health questions and decline you or charge more, under federal rules. Here are the windows that matter:
| Window | When | What it allows |
|---|---|---|
| Medicare Open Enrollment | October 15 to December 7, 2026 (changes start January 1, 2027) | Switch Original Medicare to Medicare Advantage or back; change Medicare Advantage or Part D plans. Doesn't guarantee a Medigap policy |
| Medicare Advantage Open Enrollment | January 1 to March 31, 2027 | If you're in Medicare Advantage: one change, to another Medicare Advantage plan or back to Original Medicare (plus a Part D plan) |
| Medigap Open Enrollment | 6 months starting the first month you have Part B and are 65 or older | Buy any Medigap policy sold in your state with no medical underwriting. Happens once |
| Trial right: new at 65 | Within the first year in a Medicare Advantage plan joined when first eligible at 65 | Return to Original Medicare and buy any Medigap policy sold in your state |
| Trial right: dropped Medigap | Within the first year of your first Medicare Advantage plan | Get your old Medigap policy back if still sold, or Plan A, B, C*, D*, F* or G |
| Plan leaves or you move | Up to 60 days before Medicare Advantage coverage ends, or within 63 days after | Buy Medigap Plan A, B, C*, D*, F* or G if you return to Original Medicare |
Source: Medicare & You 2027, pp. 13 and 76; CMS, Choosing a Medigap Policy (2026), pp. 17-18; 42 U.S.C. 1395ss(s)(3)(B)(v)-(vi) (Social Security Act s. 1882). *Plans C and F only for people eligible for Medicare before January 1, 2020; others get D or G instead.
The trial rights are the safety valve. If you join Medicare Advantage when you first get Part A at 65, federal law (Social Security Act s. 1882(s)(3)(B)(vi)) gives you 12 months to change your mind and buy Medigap without health questions. If you dropped a Medigap policy to try Medicare Advantage for the first time, section 1882(s)(3)(B)(v) gives you 12 months to go back.
After that, leaving Medicare Advantage during Open Enrollment returns you to Original Medicare, but the Medigap application is a separate step the insurer may underwrite. Preferring Original Medicare isn't one of the federal guaranteed-issue situations. The Open Enrollment 2027 post covers the full calendar and the Annual Notice of Change.
Washington's own Medigap rules
Washington adds protections on top of the federal floor, and they change the math for people already on the Original Medicare path.
Switching between Medigap policies, any time of year. Under RCW 48.66.045(2)(b), every Medigap issuer must issue its standardized plans B, D, G, G with high deductible, K, L, M, or N without evidence of insurability
to a Washington resident eligible for Medicare on or after January 1, 2020, if the medicare supplement policy or certificate replaces another medicare supplement policy or certificate or other more comprehensive coverage.
Subsection (2)(a) gives people eligible before 2020 the same right, with Plans C and F on the list too, and (2)(c) lets a Plan A holder move to another Plan A. In the OIC's words, if you have a Medigap plan B through N, you can switch at any time to another Medigap plan B through N,
with no written health screening (OIC).
That right is for moving from one Medigap policy to another. It doesn't cover moving from Medicare Advantage into Medigap. The OIC says that if you're switching from another type of health plan to Medigap, rules can vary and insurers may require you pass a written health screening questionnaire.
If you aren't sure whether you'd face one, call the OIC's consumer hotline at 800-562-6900 and ask for a health compliance analyst before you drop anything.
Two 2025 bills would have gone further: HB 1603 would have given guaranteed issue to people leaving Medicare Advantage, and HB 1754 would have required it during an open enrollment period. Neither moved past committee, and both were retained in present status in January 2026.
Community rating. RCW 48.66.045(3) requires Medigap issuers to set rates only on a community-rated basis: premiums must be equal for everyone on the same standardized plan form, except for spousal, payment-frequency and payment-method discounts. An issuer can keep at most two rating pools, one for people eligible by age and one for people eligible by disability or end-stage renal disease. Your Medigap premium can still change when the insurer files new rates, but not because you got older. Rate changes have to be filed with and approved by the Insurance Commissioner first (RCW 48.66.035).
The full Medigap rulebook, plan letters and all, is in my Medicare Supplement in Washington post.
Under 65 on Medicare
About 127,000 Washingtonians (CMS, June 2026) get Medicare because of a disability or end-stage renal disease rather than age. For them, the two paths aren't equally open. Medicare Advantage plans generally take anyone with Part A and Part B who lives in the service area and meets Medicare's residency rules. Medigap is harder: Washington doesn't require insurers to offer Medigap plans to people on Medicare under age 65
(OIC handbook), and the OIC warns you might not be able to buy the Medigap plan you want, or any Medigap plan, until you turn 65.
Two things help. If an insurer does sell you a Medigap policy before 65, the RCW 48.66.045 switching right covers people eligible by reason of age, disability, or end-stage renal disease.
And when you turn 65, you get a new six-month Medigap Open Enrollment Period even though you already have Part B (CMS).
How Washington splits
Washington sits close to the national middle. In March 2026, KFF counted 54% of Washington's Medicare beneficiaries with Parts A and B in Medicare Advantage, against 55% nationally (35.2 million of 64.2 million). That national share was 19% in 2007.
Source: KFF, Medicare Advantage in 2026: Enrollment Update and Key Trends (state appendix, data)
Show the numbers
| State | In Medicare Advantage |
|---|---|
| Oregon | 58% |
| California | 56% |
| U.S. | 55% |
| Washington | 54% |
| Idaho | 48% |
| Montana | 31% |
| Alaska | 2% |
Inside the state the spread is far wider. In Clark County, across the Columbia from Portland, about three in four beneficiaries are in Medicare Advantage. In Klickitat County, farther up the Columbia River Gorge, fewer than one in ten are. San Juan County and the Olympic Peninsula's Clallam and Jefferson counties lean heavily toward Original Medicare too.
Source: KFF analysis of CMS enrollment files, county appendix data (March 2026)
Show the numbers
| County | In Medicare Advantage |
|---|---|
| Clark County | 74.2% |
| Snohomish County | 66.5% |
| Spokane County | 62.0% |
| King County | 60.0% |
| Pierce County | 57.2% |
| Thurston County | 56.9% |
| Whatcom County | 50.4% |
| Yakima County | 49.5% |
| Kitsap County | 44.0% |
| Benton County | 34.7% |
| Clallam County | 24.2% |
| Jefferson County | 16.7% |
| San Juan County | 15.8% |
| Klickitat County | 8.5% |
My read: those county numbers say more about what's available locally than about which path is right. Where provider networks are thin, a network-based plan is a harder fit, and fewer people choose one. If you live in San Juan or Jefferson County, check whether the doctors and the hospital you actually use are in any plan's network before you assume Medicare Advantage works where you live. Statewide, CMS counted 796,152 Washingtonians in Original Medicare and 787,414 in Medicare Advantage and other health plans in June 2026 (CMS).
Questions to answer before December 7
Rather than a verdict, here's what I'd write down before choosing or switching:
- Your doctors and hospitals. List them. If you're considering Medicare Advantage, check each one in the plan's directory and on the Medicare.gov Plan Finder, which lets you add providers. Remember that networks can change mid-year.
- Your worst plausible year. Could you cover a plan's out-of-pocket limit, up to $9,850 in-network in 2027, plus Part D costs up to $2,400? Or would you rather pay a Medigap premium every month to keep bills small?
- Where you'll be. Months away from home, or trips abroad, change the picture.
- Your drugs. Both paths need Part D coverage. Enter every prescription in the Plan Finder; the Part D 2027 post explains the $2,400 cap.
- Your way back. If you're leaving Medigap for Medicare Advantage for the first time, you have a 12-month trial right. After that, getting Medigap again may mean health questions. Don't cancel a Medigap policy until the new coverage is confirmed.
- Your plan's letters. If you're in Medicare Advantage now, read the Annual Notice of Change your plan sent for 2027.
For free, unbiased one-on-one help, call SHIBA, the OIC's Statewide Health Insurance Benefits Advisors, at 800-562-6900 (8:30 a.m. to 4:30 p.m., Monday to Friday), or 1-800-MEDICARE (1-800-633-4227; TTY 1-877-486-2048). For more on each piece, see the Washington Medicare page, the Washington Medicare Supplement page and the Washington Part D page.
FAQ
What is the main difference between Medicare Advantage and Medigap?
Medigap is a supplement that works with Original Medicare and pays much of its cost sharing, with any provider in the U.S. that accepts Medicare. Medicare Advantage replaces how you get Part A and B coverage: a private plan with its own network rules, copays and a yearly out-of-pocket limit, usually with drug coverage included. You can't have both at once.
What is the Medicare Advantage out-of-pocket maximum for 2027?
Plans can set their own limit, but it can't exceed $9,850 for in-network Part A and B services or $14,800 for in- and out-of-network services combined in 2027. In 2026 the limits are $9,250 and $13,900. Part D drug costs have a separate cap of $2,400 in 2027.
Can I switch from Medicare Advantage to Medigap in Washington?
You can return to Original Medicare during Open Enrollment (October 15 to December 7) or the Medicare Advantage Open Enrollment Period (January 1 to March 31). Buying Medigap is a separate step: unless a federal trial right or guaranteed-issue situation applies, Washington insurers may require a written health screening. Washington's any-time switching right under RCW 48.66.045 applies to moving from one Medigap policy to another.
Your own coverage documents and federal and Washington law control what any plan or policy pays. Confirm your situation with a licensed agent, SHIBA, the Washington Office of the Insurance Commissioner or 1-800-MEDICARE, and for legal questions, an attorney.
Sources
- WA OIC news release: Medicare Open Enrollment starts Oct. 15 for 2027 plans (Oct. 14, 2026)
- CMS: Medicare & You 2027 handbook
- CMS: Choosing a Medigap Policy (2026)
- Medicare.gov: How Medigap works
- Medicare.gov: Compare Medigap plan benefits
- Medicare.gov Plan Finder
- CMS: 2026 Medicare Parts A & B premiums and deductibles
- CMS: Out-of-pocket limits for Medigap Plans K & L, calendar year 2027
- CMS: 2027 Medicare Advantage and Part D Rate Announcement
- KFF: Medicare Advantage out-of-pocket limits, variation and trends (May 28, 2026)
- KFF: Medicare open enrollment FAQ on comparing Medicare Advantage options (2027 limits)
- KFF: Medicare Advantage in 2026, enrollment update and key trends
- KFF: state appendix data, Medicare Advantage penetration, March 2026
- KFF: county appendix data, Medicare Advantage penetration, March 2026
- CMS: Medicare monthly enrollment
- 42 CFR 422.101, requirements relating to basic benefits
- 42 CFR 422.112, access to services
- 42 CFR 422.113, emergency and urgently needed services
- 42 CFR 422.138, prior authorization
- 42 CFR 422.568, standard organization determinations
- 42 CFR 422.572, expedited organization determinations
- 42 U.S.C. 1395ss (Social Security Act s. 1882), Medigap guaranteed issue and trial rights
- RCW 48.66.045, replacement policies and community rating
- RCW 48.66.035, Medigap rate filing and approval
- WAC 284-66-064, Medigap benefit standards (foreign travel)
- Washington Legislature: HB 1603 (2025-26)
- Washington Legislature: HB 1754 (2025-26)
- WA OIC: Medigap (Medicare Supplement) plan coverage and costs
- WA OIC/SHIBA: What you need to know about Medigap plans (2026)
- WA OIC: Free Medicare help from SHIBA
This article is for general educational purposes only and is not legal, tax or insurance advice. Coverage depends on the actual policy, its terms, conditions and exclusions, and state law. Maru Insurance · WA License (WAOIC) #1365574 · FL License #G363233 · NPN 22261820.