Social Security & Medicare

That's it. They have nothing more to do with the policy, and it's generally one of the most expensive. All the companies offer the exact same coverage, and all of them have to pay their percentage as long as Medicare approves the claim to begin with. Check here: http://www.ehealthinsurance.com/medicare/supplement to compare prices for all the Plan F providers in your area. While you're at it, you might want to check Plan N too. You might be amazed by the variations in price for exactly the same product.

BTW, check the Part D policies too. It's crucial to make sure that your few generics are actually covered at a decent price, and each insurer has a slightly different set of meds, in different coverage tiers, at different prices for each tier. Again, AARP doesn't provide the insurance and they may not provide the best deal for you. Find the best premiums ands then go to each company's website to look up your meds and see what they'll charge you. The difference can cost (or save) you hundreds of dollars.

It's a pain to do this, but it really is worth it.