[oh8eleven]

if there is an advantage to starting their Social Security benefits earlier, to avoid the premium increase?
If you're not on SS or Medicare how would you even know about a future premium increase?
Another question - if straight Medicare covers about 80% of a subscriber's medical costs, why not throw in the "missing" 20% and cover it all?
And - why are some Advantage and (especially) Supplemental plans so expensive if they're only covering that missing 20%?

[justlurking]

If you're not on SS or Medicare how would you even know about a future premium increase?

You read the news, like this article.

You can also use the premium calculator here:

Eligibility & Premium Calculator

That presumes they update it before the end of the year. Currently, it estimates the 2015 premium. They'll also have to add an option about whether you are receiving Social Security benefits.

Another question - if straight Medicare covers about 80% of a subscriber's medical costs, why not throw in the "missing" 20% and cover it all?

Two reasons: it will add 25% to a program that is already underfunded, and "free" medical care with no co-pay will increase consumption even more.

And - why are some Advantage and (especially) Supplemental plans so expensive if they're only covering that missing 20%?

The supplemental programs are funded by premiums, and don't have the advantage of being funded by the government to make up the shortfall.