Medicare Advantage plans average $0 to $59 a month in extra premium on top of Part B, bundle in dental, vision, and hearing coverage, and are legally capped at $9,250 in yearly out-of-pocket costs for in-network care in 2026, but they route you through a network and prior authorization. Original Medicare paired with a Medigap plan and a standalone Part D drug plan typically runs $300 to $600 a month combined, with no network at all and no out-of-pocket cap needed because Medigap picks up almost everything Medicare doesn't. The real choice isn't which one is "better," it's whether you'd rather pay less monthly and accept a spending ceiling and a network, or pay more monthly for open access to any doctor who takes Medicare. Open enrollment for 2027 coverage runs October 15 through December 7, 2026, and this is also the one window where switching is simple. After that, it gets harder.
What's the Real Cost Difference Between Medicare Advantage and Original Medicare?
Medicare Advantage is cheaper month to month for most people, but Original Medicare plus Medigap is more predictable, and the gap is bigger than most comparisons admit. According to KFF's analysis of 2026 CMS data, roughly 75% of Medicare Advantage enrollees pay no premium beyond what they already owe for Part B ($202.90 a month in 2026), and the national average supplemental premium across all plans is just $15 a month, up from $13 in 2025. Among the roughly 25% of enrollees who do pay a plan premium, the average is $59 a month, which includes built-in Part D drug coverage for most of those plans.
Original Medicare requires that same $202.90 Part B premium from everyone, no matter which path you choose, plus a separate Medigap premium and a separate Part D premium. Medigap Plan G, the most comprehensive plan most new enrollees can still buy, isn't priced nationally. 2026 rate filings show increases of 12% to 26% in many states, and real quotes for the same plan from the same insurer can differ enormously by age and location: one 67-year-old reported in late 2026 being quoted $385 a month for Plan G, while his neighbor on the identical plan from the identical company paid $165. Add a Part D plan (the 2027 national base beneficiary premium is set at $41.33) and a realistic all-in Medigap-plus-Part D budget lands somewhere between $150 and $450 a month on top of Part B, depending entirely on your state, age, and which insurer you pick.
What Do You Actually Get With Original Medicare Plus Medigap?
You get access to any provider in the country who accepts Medicare, which is the overwhelming majority of U.S. doctors and hospitals, with no referrals and no prior authorization for most services. Medigap Plan G covers essentially all of Medicare's cost-sharing except the Part B deductible, projected at roughly $292 for 2027 (up from a confirmed $283 in 2026), so your yearly medical costs are effectively capped at that deductible plus your fixed premiums, with no surprise bills for covered care. What you don't get automatically is dental, vision, or hearing coverage, those are separate purchases, and Medigap pricing tends to climb with age under most insurers' "attained-age" pricing models, meaning your premium can rise every year even if your health doesn't change.
What Happens If You Pick Medicare Advantage and Then Change Your Mind?
If you enrolled in Medicare Advantage when you first became eligible at 65, you get a 12-month trial right to switch to Original Medicare and buy a Medigap policy with guaranteed issue, meaning no health questions and no ability for the insurer to turn you down or charge you more. Once that trial right expires, switching from Medicare Advantage back to Medigap in most states requires medical underwriting, so an insurer can deny you or charge a higher rate based on your health history, unless you hit a specific guaranteed-issue trigger like your Advantage plan leaving your service area or exiting Medicare entirely. A handful of states, including New York, Connecticut, Massachusetts, and Maine, guarantee issue on Medigap year-round regardless of health, but that's the exception, not the rule. This is the gap that catches people: Medicare Advantage can look reversible when you're 65 and healthy, and much less reversible once you've had a few diagnoses and want out at 72.
What's Actually Changing for 2027 Coverage?
Two cost figures for 2027 are already locked in by law, and two are still projections you'll want to confirm before December 7. The Part D deductible rises to a confirmed $700 in 2027, up from $615 in 2026, and the Part D out-of-pocket cap rises to a confirmed $2,400, up from $2,100, both set under the Inflation Reduction Act's drug pricing rules. The Part B premium and deductible are not yet final: the 2026 Medicare Trustees Report projects the 2027 Part B premium at roughly $209.50 a month (versus a confirmed $202.90 in 2026) and the deductible at roughly $292 (versus $283), but CMS typically doesn't confirm the official numbers until mid-November, so treat those two as estimates until your plan's Annual Notice of Change or Medicare.gov shows the finalized figures.
So How Do You Actually Decide?
- You want the lowest possible monthly cost and don't mind a network: Medicare Advantage fits, but re-check your plan's Annual Notice of Change every single year, since premiums, networks, and covered drugs can all change for the next plan year even if you don't touch anything.
- You want to see any doctor anywhere with no prior authorization and can absorb a higher fixed monthly cost: Original Medicare plus Medigap Plan G plus a separate Part D plan is built for that, at the cost of paying for dental and vision separately.
- You're turning 65 this enrollment period and genuinely unsure: your 12-month trial right exists specifically so you can try Medicare Advantage now, while switching to Medigap with no health questions is still guaranteed if it doesn't work out. That option disappears later.
- You've been on Medicare Advantage for years and want to leave: check your state's guaranteed-issue rules before canceling anything. Walking away from Advantage coverage without a Medigap option already lined up can leave you facing full medical underwriting with no fallback.
- Either way, compare using your real ZIP code and your real drug list on Medicare's official Plan Finder, not a generic premium number. The plan that's cheapest on paper can be the most expensive one once your actual prescriptions and doctors are factored in.
The December 7 deadline is firm, and outside of a few narrow exceptions, missing it means living with your choice for all of 2027. If you're weighing this decision as part of a broader retirement timeline, our breakdown of Social Security claiming ages covers the other major 65-and-up decision most people are making around the same time, and our look at HDHP vs. PPO health plans walks through the same network-versus-flexibility trade-off for anyone still on employer coverage before Medicare kicks in.
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