VA will not supplement Medicare A and B, and relying on the VA solely will not cover your civilian medical expenses. Also relying on the VA assumes that you can control when and where you go for care when sick or injured.
There are numerous Supplemental Medicare Policies offered by insurance companies that cover the deductibles and co-insurance payments of Medicare Part B. There are also Medicare Advantage plans that manage the Medicare program for you that offer various plans.
The Medigap policies are all the same, all over the country. If you get Plan F from one company, or in one state, it will be identical to all of the Plan F policies anywhere in the USA. That is mandated by law. However, the cost of that policy varies quite a bit from one company to another. Before you buy, check out at least 5-6 different companies. I was amazed at just how much the cost varied from one company to another.
VA prescription drug coverage is considered creditable drug coverage under the Medicare Part D. This means that if you choose to enroll in part D after your initial enrollment period, you will not have to pay a penalty premium for part D when you had creditable coverage.
When you become eligible for medicare, basically you have a 6 month period where pre-existing conditions do not apply. After that though, you have to go through underwriting and may face a pre-existing condition limitation.
In some cases, a Medigap insurance company can refuse to cover health problems for up to six months, if you had the health problem before the policy started. This is called a “pre-existing condition waiting period.” The insurance company can only use this kind of waiting period if your health problem was diagnosed or treated during the six months before the policy started. This means that the insurance company can’t make you wait for coverage of a pre-existing condition just because it thinks you should have known to see a doctor for a health problem.
On the medigap pre-existing limitation, Federal Medicare law provides a minimum set of rules regarding Medigap for people with Medicare anywhere in the country. A state can choose to offer its residents more protections and rights related to Medigap than the federal minimum. In such cases, state law supercedes federal law. For example, federal law does not require insurance companies to sell Medigap policies to people under age 65 but some states do. Federal law provides the coverage requirements for various medigap plans (plan A, B, etc) but states decide which plans can be sold in their jurisdiction. So it may be that California counts VA medical as creditable coverage while the next state may not.