Medicare Advantage vs Medigap in 2026: Which Wins?

The 60-second rule

If you are healthy and price-sensitive, Advantage usually wins the typical year. If you want cost certainty — or your health is already complicated — Medigap is the buy. And treat the age-65 choice as permanent, because in most states switching back later requires passing medical underwriting. That is the whole guide in three sentences. The premium gap seduces everyone toward Advantage ($14 a month vs $240+ for Plan G plus Part D); the bad-year math is what you are actually buying insurance against. Everything below is the evidence — and the trap almost nobody hears about until they are standing in it.

How the two paths really price a year

Start with the floor nobody escapes: everyone pays the $202.90-a-month Part B premium on both paths — $2,434.80 a year, usually deducted from your Social Security check. High earners pay more through IRMAA (up to $689.90 a month) on both paths too. Anyone quoting a “$0 Advantage plan” means $0 on top of Part B, not $0 total. On top of that floor:

Path 1 — Original Medicare + Medigap Plan G + standalone Part D. You pay three premiums: Part B ($202.90), Plan G (typically $150–$300+ a month depending on age, ZIP, and insurer), and a Part D drug plan (typically $20–$80). In exchange, Plan G covers everything except the $283 annual Part B deductible — the $1,736 hospital deductible, the 20% coinsurance (which has no cap under Original Medicare), skilled-nursing coinsurance, all of it. Your medical year costs the premiums plus $283, whether you are healthy or hospitalized. There is no network: any doctor or hospital that takes Medicare takes you.

Path 2 — Medicare Advantage (Part C). A private plan bundles A, B, and usually D into one package. The average premium is about $14 a month in 2026, and $0-premium plans are everywhere — but every doctor visit, lab, scan, and hospital day carries a copay or coinsurance, accumulating up to the plan’s in-network out-of-pocket maximum (legally capped at $9,250 for 2026; the median plan sets it near $5,900). Drugs usually ride along with their own $2,100 annual cap. Most plans are HMOs (about 57% in 2026): a network, referrals, and prior authorizations are part of the deal.

The $1,495 worked example, line by line

Plan G $200 a month, Part D $40 a month, Advantage $14 a month, a typical health year ($1,500 of Advantage cost-sharing — a few specialist visits, labs, an ER trip):

Medigap path: $202.90 + $200 + $40 = $442.90 a month × 12 = $5,314.80 in premiums, plus the one bill Plan G does not cover — the $283 Part B deductible — for $5,597.80 all-in. Every visit and stay after January: $0 at the point of care.

Advantage path: $202.90 + $14 = $216.90 a month × 12 = $2,602.80 in premiums, plus $1,500 of copays and coinsurance, for $4,102.80. Advantage wins by $1,495. This is the year the $0-premium mailers are selling you — and the math is real, as far as it goes.

The $6,255 flip (the year that matters)

Now make it a bad year: surgery, a hospital stay, months of specialists — the kind of year nobody plans. The Advantage cost-sharing runs to the $9,250 in-network cap: $2,602.80 + $9,250 = $11,852.80. The Medigap side? $5,597.80 — unchanged to the dollar, because Plan G already covered everything except the $283 deductible. Medigap wins by $6,255.

That flip is the entire decision compressed into two numbers. Advantage is cheap to hold and expensive to use; Medigap is expensive to hold and nearly free to use. The question is not “which is cheaper” — it is “how much uncertainty do I want to buy off, and at what price?” A healthy 65-year-old can reasonably bet on several $1,495-style years before one bad year erases the savings; a 72-year-old with heart disease, diabetes, and arthritis is already living in the high-use rows, where Medigap’s flat $5,597.80 beats Advantage’s meter running toward $9,250.

When Advantage wins anyway

Three honest cases for Advantage. One: you are healthy and the premium gap is real money. $2,600 a year vs $5,600 a year is a $3,000 annual difference — over a decade of healthy years, that is $30,000 kept, against one hypothetical bad year. Two: the extras matter to you. Advantage plans bundle dental, vision, hearing, gym memberships, and OTC allowances that Original Medicare does not cover at all — Medigap does not add them either. Three: you value the cap over the network. The $9,250 ceiling is real protection; Original Medicare without Medigap has no ceiling at all, which is why nearly nine in ten traditional-Medicare enrollees carry some supplement.

When Medigap wins anyway

Three honest cases for Medigap. One: your health is already complicated. Multiple chronic conditions mean the Advantage meter runs every month — specialist copays, imaging coinsurance, drug tiers — and you will feel the difference between “$0 at the visit” and “$45 at the visit” fifty times a year. Two: you want any doctor, anywhere. No networks, no referrals, no prior authorizations, no “is this specialist in-network” phone calls — and that matters most exactly when you are sickest. Three: you are buying certainty, not the cheapest year. The Medigap premium is the price of knowing your medical year costs $5,597.80 no matter what — a number you can budget around, unlike a cap you hope not to meet.

The one-way door (read this before you choose)

Here is the trap: switching from Advantage back to Medigap later usually requires passing medical underwriting — and insurers in most states can deny you or charge more for the exact conditions that make you want to switch. Your guaranteed-issue rights are narrow: the first 6 months with Part B (your Medigap open enrollment at 65), a 12-month trial right if Advantage was your first Medicare coverage, and 63 days after a plan non-renewal or a move out of the service area. The state exceptions: Connecticut, New York, Massachusetts, and Maine offer year-round or annual guaranteed-issue windows, and California, Oregon, Washington, Nevada, Idaho, Illinois, Kentucky, and Louisiana have birthday rules for switching Medigap plans without underwriting. Everyone else: choose at 65 like it is permanent, because for practical purposes it is. (Leaving Advantage for bare Original Medicare is always allowed — it is the Medigap policy afterward that requires underwriting.)

The December 7 deadline and the windows

Fall open enrollment runs October 15 – December 7 — the annual window to switch Advantage plans, join or drop Part D, or return to Original Medicare for the next year. A second window, the Medicare Advantage open enrollment (January 1 – March 31), lets current Advantage members switch plans once or drop back to Original Medicare. Two more dates that cost real money if missed: your initial enrollment (the 7 months around your 65th birthday — miss it and Part B and Part D late penalties can follow you for life) and the Part D $2,100 cap math if you take expensive brand drugs. Free, unbiased help exists in every state: your SHIP (State Health Insurance Assistance Program) counselors do not sell insurance.

Three mistakes to avoid

1. Choosing on the premium alone. The $14-vs-$240 monthly gap is the most advertised and least complete number in Medicare. Price a bad year — the $9,250 cap against Medigap’s flat total — before you decide the cheap premium is the cheap plan. The calculator’s “expected MA medical bills” field exists precisely for this.
2. Assuming you can switch back later. The single most expensive assumption in this guide. Outside the trial right and the handful of protected states, “I’ll start with Advantage and upgrade to Medigap if I get sick” is a plan that requires insurers to underwrite you after you get sick — which is exactly when they can say no.
3. Forgetting Part D on the Medigap side. Medigap covers medical gaps, not drugs — you need the standalone Part D plan (and its premium) for the comparison to be honest. The good news since 2025: drug out-of-pocket is capped at $2,100 a year on both paths, so price the premium, not the catastrophe.