Turning 65 and signing up for Medicare now. I found it to be somewhat confusing, and information sketchy at best. For my situation - I chose traditional Medicare A & B and Hi Deductible "F" supplement. I will use the VA for Part D as it qualifies and presents no penalties for not signing up for D at 65. Can always change my mind if I leave the VA.
A (hospital) & B (medical) traditional Medicare are an automatic sign up if you're already on Social Security. The Medicare booklet mentioned will tell you how to sign up if you're not on SS (read that area carefully).
C is Advantage (HMO style) Medicare A & B run by private insurance companies and may or may not have drug (Part D) coverage. There usually are "deductibles and in-network" compliance issues associated with regional coverage (choose carefully here also).
D is drug coverage and usually chosen with traditional supplement and not advantage plans (again choose carefully).
Medigap or supplemental coverage is to cover the costs you pay out of pocket with traditional Medicare coverage (A & B) - not advantage plans. Again referenced material here will explain all the options. SHIP is a independent source of assistance/information, but understaffed and weren't all that knowledgeable in our area.
Did attend a Medicare seminar at our local library. This was put on by an independent insurance broker. Did a good job explaining the choices, and is paid by the insurance companies (you don't pay to use his service). Keep in mind that he will help you, but you will get one of the insurances he is licensed to sell (there are others out there that might be less expensive). FYI - all supplemental policies are regulated by the government and the only differences are the prices. I signed up for supplemental insurance (High deductible "F") w/o the use of the broker as it was cheaper than what he offered - was actually another arm of the insurance company that did not use brokers. Sorry to say - both brokers I contacted disappeared when it became apparent I was not going to sign up for "F" or an Advantage plan where they make the most money.
You are guaranteed acceptance at 65, but acceptance by insurance companies is not guaranteed after that initial enrollment. This gives them a chance to price your policy based on medical history - you're older and may be suffering from health issues (you may be stuck with your insurer).
FYI - the most popular Medigap policy is "F" which covers most everything (even if you should find yourself in situation where Medicare is not accepted - believe it covers up to 15% of charges over Medicare coverage). "F" is scheduled to be eliminated by Congress as of 2020. If you take it - the pool of enrollees will stop and costs for "F" will be most likely going up more than the other Medigap coverages.
"G" is the same as "F" and will not be going away, so will most likely become the popular choice after 2020 (and now if you know this fact, or your broker is good to you and not just interested how much money he makes). "G" does not cover the Part "B" Medicare coverage deductible of $166.00 annually (yes, it's confusing). After that - "G" and "F" Medigap coverage are the same. "G" price difference might be better than "F" to where your part "B" Medicare deductible is covered in under a couple of months of "F" payment difference.
Be cautious of giving out your information to any online companies. They even will warn you about others who only want to get paid for getting you signed up and won't be around to assist you in the future
State by state regulations (meddling) will also affect the cost of supplemental policies. Hope this info helps....