If you are turning 65 this year, the paperwork in front of you probably includes two acronyms that sound almost identical and behave nothing alike.
One works like a health plan you use inside a network.
The other works like a backup payer that picks up what original Medicare leaves behind.
Choosing wrong can cost you thousands in a year you did not plan for.
Medicare Advantage, often called Part C, replaces the way you get original Medicare.
You stay enrolled in Medicare, but a private insurer administers your benefits, usually through an HMO or PPO.
Premiums can look tempting, sometimes near zero beyond the standard Part B charge, and many plans throw in dental, vision and a drug benefit.
Advantage plans use networks, prior authorizations and referral rules.
A specialist you have seen for a decade may sit outside the network.
A hospital stay may need approval before it happens.
Out-of-pocket costs are capped each year, but that cap can run into the thousands before it protects you.
Medicare Supplement plans, also called Medigap, work the other direction.
You keep original Medicare as your primary coverage and pay a private insurer a monthly premium to cover much of what Medicare does not, including coinsurance and hospital deductibles.
You can see any provider in the country who accepts Medicare.
Medigap premiums are typically higher than Advantage premiums and rise with age in most states.
You also need a separate Part D drug plan.
But once you pay the premium, a good Plan G leaves you responsible mainly for the Part B deductible and small gaps.
The real dividing line is your health and your tolerance for rules.
If you have ongoing conditions, take expensive medications, or want to see specialists without asking permission, Medigap tends to be the calmer financial path.
If you are healthy, take few drugs, and want the lowest possible monthly cost, Advantage can work well as long as you understand the network.
Timing matters more than most people realize.
When you first enroll in Medicare at 65, you generally get a guaranteed window to buy a Medigap policy without answering health questions.
Miss that window, and in most states an insurer can charge you more or turn you down based on medical history.
Switching from Advantage back to Medigap later is not always possible on affordable terms.
Read the annual notice of change every fall, even if you love your plan.
Formularies shift, networks shrink and copays creep up.
A plan that fit your budget two years ago may not fit today.
Before you decide, list every doctor, every prescription and the pharmacy you actually use.
Then price both paths with real numbers, not marketing brochures.
A licensed counselor through your state's Senior Health Insurance Program can walk you through it for free.
My take: the cheapest premium is rarely the cheapest plan.
For most people managing a chronic condition, Medigap buys peace of mind that Advantage cannot match.
Final Thoughts
For healthy retirees on a tight budget, Advantage can be a reasonable bet, as long as you go in with your eyes open.