Medicare Advantage vs Medigap: How to Choose

For retirees with meaningful income, this is one of the most consequential elections in retirement. The wrong choice at 65 can be nearly impossible to undo at 72.

How each model works

Original Medicare + Medigap (Medicare Supplement): You keep traditional fee-for-service Medicare (Parts A and B) and buy a private supplemental policy — most commonly Plan G — that covers the gaps Medicare doesn't pay. Plan G covers 100% of Part A coinsurance, Part B coinsurance (the 20% gap), the Part A deductible ($1,736 per benefit period in 2026), and skilled nursing coinsurance. Your annual out-of-pocket is essentially your monthly premium plus the $283 Part B deductible. Every Medicare-accepting provider in the country is available to you — no network, no referrals.

Medicare Advantage (Part C): A private insurer manages your Medicare benefits under a bundled plan, typically an HMO or PPO. Many plans charge $0 in monthly premium (you still pay Part B regardless) and usually include Part D drug coverage. The tradeoff: network restrictions, prior authorization requirements, and cost sharing — copays, coinsurance, and deductibles — that accumulate quickly when you use care heavily. CMS limits total in-network out-of-pocket to $9,250 in 2026, but most beneficiaries don't hit that ceiling.

The enrollment window you cannot miss

This is not a theoretical risk. Someone who enrolls in Medicare Advantage at 65, develops a serious illness at 70, and wants to switch to Medigap will find that most insurers will decline the application outright — or price Plan G at two or three times the standard rate. Exceptions: New York, Connecticut, Maine, and Massachusetts have year-round guaranteed-issue rules. Most other states do not.

The 12-month trial right: Federally, you have a one-time right to switch from Medicare Advantage back to Original Medicare + Medigap with guaranteed issue within the first 12 months of your initial MA enrollment. After that window closes, you're subject to medical underwriting in most states. This is your safety valve — but it only works once.

Annual cost comparison

Enter your actual numbers. Medigap premiums vary significantly by age, insurer, and state — get real quotes from at least three carriers before deciding. The defaults below are national averages for a 65-year-old.

The factors money doesn't capture

Provider access

Original Medicare + Medigap gives you access to any Medicare-accepting provider in the country — cancer centers, academic medical centers, out-of-state specialists, Mayo, MD Anderson, whatever you need. Medicare Advantage HMOs restrict you to a network; out-of-network care often isn't covered except in emergencies. PPOs allow out-of-network but at higher cost sharing. For retirees who travel frequently or want access to top specialty programs, provider access is often the deciding factor.

Prior authorization

Medicare Advantage plans routinely require prior authorization for specialist referrals, imaging, procedures, and inpatient stays. Denials are not uncommon and appeals take time — time you may not have during a medical crisis. Original Medicare does not require prior authorization for most medically necessary services.

Predictability and income

Medicare Advantage is structurally a bet that you'll stay healthy. In healthy years, the lower premiums typically win on cost. In sick years, cost sharing can accumulate to thousands — up to the plan's MOOP — and the uncertainty itself has planning costs. For retirees with substantial assets, paying the Medigap premium to eliminate that variance is often the right call. For retirees on tighter fixed income where the Medigap premium itself is the binding constraint, MA can make sense if the network and health risk are well understood.

A common misconception: IRMAA applies either way

Some retirees believe that choosing Medicare Advantage avoids the IRMAA surcharge on Part B premiums. It does not. IRMAA applies to your Part B premium regardless of whether you're enrolled in Original Medicare or Medicare Advantage — Part B enrollment is required for both. The same two-year MAGI lookback applies. Choosing MA does not reduce IRMAA exposure by a dollar.

What high-income retirees typically choose

Retirees with retirement MAGI above $130K commonly land on Original Medicare + Plan G for three reasons: (1) they're already paying a high Part B premium via IRMAA and the incremental cost of a Medigap premium is smaller relative to their overall healthcare spend; (2) the predictability of zero cost sharing simplifies planning; and (3) they often have the financial flexibility — Roth conversions, qualified charitable distributions, capital-gain harvesting — to optimize MAGI year by year, which a specialist advisor models alongside their Medicare elections.

The decision, plainly

If you want full provider freedom, predictable costs, and you're enrolling during the Medigap guaranteed-issue window — Plan G is the stronger choice for most retirees with meaningful assets. If you're on a fixed income, in good health, and comfortable working within a network, MA can make economic sense. The right answer depends on your income, health trajectory, provider preferences, and IRMAA situation — exactly what a specialist models with you.