You can look at it as post-paid vs. pre-paid, but that isn’t really how it is structured.
Essentially, there is single-payer Medicare (Parts A, B, D) or Medicare Advantage (Part C), which means you sign on with a private insurance company to manage your coverage.
Let’s say you get a Medicare Advantage plan with United Health (the AARP-linked company). Let’s say that the UH plan in your area is also an HMO (as it would be for me). That means that you have private insurance with all the same benefits and drawbacks that you always had – deductibles, copays, restricted networks, and the need to pre-approval for many procedures.
The difference is that if you were paying full cost for insurance coverage before, you see a big drop in rates. So maybe your monthly premium at age 64 was $900 and now at age 65 you are paying $100/month. Seems great.
Here’s a comment I heard from one agency: “Everyone on Medicare Advantage loves it … until they get sick.”
On the other hand, a Medicare Supplement (Medigap) policy is not health insurance as you’ve known it – instead it is secondary coverage, and your Medicare Parts A & B are your primary coverage – plus you have to buy your Part D Supplement plan separately. More expensive up front – but you get all the benefits of a single payer system. If you’ve bought Plan F (the most comprehensive) then basically you never have to pay anything BUT the premiums, for any service that is covered by Medicare. No copays, no co-insurance, no deductibles. You go to any doctor or facility that accepts Medicare, and its free. Medicare, and Medicare alone, will decide if something is covered – your Medicare Supplement company doesn’t make that decision. So if Medicare refuses coverage on something, then you have to take it up with Medicare – your supplement pays for the costs that Medicare doesn’t cover (such as copays) – but it doesn’t pay for the procedures that Medicare doesn’t cover. Along the same lines, if Medicare does approve the hospitalization or procedure, the Medicare Supplement company can’t invent some sort of excuse as to why they won’t cover their share. It’s pretty much like an umbrella policy for Medicare – they fill in the gaps for all the things that Medicare covers but doesn’t pay 100%.
Either way you can run into a problem of wanting a procedure such as cosmetic surgery that won’t be covered. And I really don’t know what happens when you get some procedure like a lab test that you think is covered and it turns out that it isn’t — I am hoping that the providers will know enough to tell you upfront that Medicare won’t cover it, but since I haven’t started Medicare yet, I don’t know whether that is how it really works. I think that if a doctor or lab is accepting Medicare “assignment” they are the ones who get stuck if they provide an uncovered service – not the patient – but I am not entirely certain of that.