A 67-year-old in good health sees an obvious answer in her Medicare options. Original Medicare plus a Medigap Plan G runs about $220 a month on top of the Part B premium. A nearby Medicare Advantage plan charges $0. Her doctor is in network, prescription drug coverage is built in, and a gym membership comes with the package. Why pay an extra $2,640 a year?
Then she receives a cancer diagnosis. Suddenly, network restrictions, prior authorization requirements, and out-of-pocket exposure matter more than the monthly premium. The comparison looks very different than it did when she was healthy.
Who Is This Article For?
This article is for the reader weighing that exact decision: a relatively healthy person between ages 65 and 70 choosing initial Medicare coverage, or a current Medicare Advantage enrollee deciding whether to stay put during open enrollment. If you already have a chronic condition that requires frequent specialist care, the answer is often less straightforward. If your household income sits comfortably below the first IRMAA threshold of $109,000 for a single filer or $218,000 for a married couple filing jointly, IRMAA is not part of this decision. The question here is narrower: which structure costs less in a healthy year, and which one provides the strongest protection when healthcare needs become expensive.
The Healthy-Year Math
In a year where she sees her primary care doctor twice, gets a flu shot, and refills two generic prescriptions, the Advantage enrollee pays the standard $202.90 monthly Part B premium and almost nothing else. Copays for those office visits might run $0 to $40 apiece.
The Original Medicare plus Plan G enrollee pays the same $202.90 Part B premium, plus the $220 Plan G premium, plus a standalone Part D drug plan. Plan G covers everything Original Medicare leaves behind except the $283 annual Part B deductible. Once she pays that deductible, her cost-sharing for the rest of the year is essentially zero.
Healthy-year tally: the Advantage enrollee may save several thousand dollars a year in premiums and cost sharing compared with Original Medicare plus Plan G. The exact amount depends on local Medigap premiums, drug-plan costs, and the specific Advantage plan.
The Cancer-Year Math
Run the same comparison through a year with surgery, chemotherapy, imaging, and a five-day inpatient stay.
The Medicare Advantage enrollee is exposed to the plan’s out-of-pocket maximum. CMS sets the 2026 federal ceiling at $9,250 for in-network care and $13,900 for plans that include a combined in-network and out-of-network maximum. Most plans set lower limits. The enrollment-weighted average in-network maximum is $5,421 in 2026, although individual plans vary. Check the Evidence of Coverage for the number that applies to your plan.
One important limitation: the in-network maximum does not include Part D drug spending. Network restrictions can also matter when a specialist, cancer center, or other provider is outside the plan’s network. Depending on the plan structure, those situations can increase costs or limit access to care.
The Original Medicare plus Plan G enrollee faces a different calculation. After paying the annual Part B deductible and monthly premiums, Plan G generally covers the Part A hospital deductible, Part B coinsurance, and most other Medicare-approved cost sharing. The result is highly predictable out-of-pocket exposure, even during an expensive year of treatment.
In many high-cost medical scenarios, the combination of Original Medicare and Plan G produces lower out-of-pocket costs than a Medicare Advantage plan that reaches its maximum. The exact difference depends on the Advantage plan’s cap, the Medigap premium, prescription drug costs, and whether specialized care requires out-of-network providers.
The Break-Even and the Switch-Back Trap
The tradeoff comes down to how much value you place on protection against a bad year. A reader who expects relatively low healthcare utilization may spend less over time with a Medicare Advantage plan, particularly if the plan carries a $0 premium. A reader concerned about future cancer treatment, heart disease, stroke, or other high-cost conditions may find the predictability of Original Medicare plus Plan G worth the additional monthly premium.
The decision becomes more complicated after a diagnosis. In most states, switching from Medicare Advantage back to Original Medicare and purchasing a Medigap policy later can require medical underwriting. Insurers may decline the application or charge higher premiums based on health status. A handful of states, including New York, Connecticut, Massachusetts, and Maine, provide broader guaranteed-issue protections, but the federal default in most states is far less forgiving. That is why many Medicare advisers view the initial Medigap decision as more consequential than it appears at age 65.
What To Do
- Pull your current or prospective Advantage plan’s Evidence of Coverage and write down the in-network and combined out-of-pocket maximums. Compare to the federal ceiling and the $5,421 average.
- Get three Plan G quotes from your state’s Medigap rate comparison page. If your local average lands well under $220, the break-even shifts further toward Plan G.
- If you are inside your one-time 6-month Medigap open enrollment window, decide before it closes. Outside that window, in most states, the switch back to Original plus Medigap requires underwriting.
Source note: figures reflect 2026 plan-year rules from the CMS “2026 Medicare Parts A & B Premiums and Deductibles” fact sheet and KFF’s 2026 Medicare Advantage analysis.
Top Gaining Stocks
Top Losing Stocks