Medicare Supplement (Medigap)

What it actually is

A Medicare Supplement, usually called Medigap, does not replace Original Medicare. It sits alongside it and pays some or all of the share Medicare leaves to you, such as the Part A hospital deductible and the twenty percent coinsurance on Part B services.

The plans are standardised by letter. A Plan G from one insurance company covers exactly the same things as a Plan G from another. What differs is the monthly premium, the company's service, and how steeply they raise rates over time.

Who it tends to suit

• People who travel, or who spend part of the year in another state
• People seeing specialists across several hospital systems
• People who want predictable costs and will pay monthly for that predictability
• People who do not want to think about networks or referrals at all

Who it tends not to suit

• People for whom the monthly premium is the deciding factor
• People who rarely use care and would rather pay when they do
• People who want dental, vision and other extras bundled in, since Medigap does not include them

The timing detail that matters most

When you first enrol in Part B at 65 or later, there is a one-time window during which a Medigap policy generally cannot turn you down or charge you more because of your health history. That window does not come back.

Outside it, in most states, applying means answering health questions and the company can decline you. That is what makes the first Medicare decision meaningfully harder to reverse than the second, and it is worth understanding before you choose rather than afterwards.

A few states have their own rules that add protections. Maryland, for example, has a birthday rule that opens a yearly window to change a Supplement without health questions.

Drugs are separate

Medigap does not include prescription coverage. It is normally paired with a standalone Part D plan, and that Part D choice deserves the same attention as the Supplement itself, because every plan covers a different list of drugs at different tiers.