What a Medicare Supplement plan actually pays

A Medicare Supplement, also called Medigap, is a private policy that pays some of the cost sharing left after Original Medicare pays a claim. It sits on Parts A and B. It is not another name for Medicare, and it is not a Medicare Advantage plan.

What the policy pays

Original Medicare decides whether a service is covered and what it allows. The Supplement then looks at the leftover patient share — the Part A hospital deductible, Part B coinsurance, and, on some lettered plans, the Part B deductible.

Most states sell standardized lettered plans. Two people with “Plan G” from different companies are buying the same covered cost-sharing items. The premium and the company name can differ. The letter is the benefit design.

A Supplement does not create a new hospital benefit. If Original Medicare would not pay the underlying claim, the Supplement usually has nothing to add.

What it does not replace

You keep Part A and Part B. The red, white, and blue card still names those parts. The Supplement policy is a second contract that follows Medicare’s payment on a claim.

A Supplement is not designed to run with Medicare Advantage. Advantage is a private plan that pays Part A and Part B claims in place of Original Medicare. A Supplement follows Original Medicare’s leftover share. Those two arrangements are not stacked.

Retail prescription drugs are usually a Part D question, not a Supplement question. Extra dental or vision extras that some Advantage plans advertise are not the job of a standard Medigap policy.

The usual mix-up

People treat a Supplement as if it replaced Medicare, or as if it were the same product as Advantage. The Supplement pays cost sharing on Original Medicare. Advantage is a different way of receiving Part A and Part B coverage.

A card from the Supplement company does not enroll you in Advantage. An Advantage card does not add Medigap cost-sharing rules on top.

What to read on the document

On the policy, read the plan letter and whether you have Part A and Part B. On a processed claim, read what Original Medicare allowed and what patient share remains. Then match that leftover line to the Supplement’s explanation of benefits. If a clinic says you need a Supplement referral, or that the Supplement is your Advantage plan, ask which contract they are reading — the Medicare card, the Advantage contract, or the Medigap policy.

Educational only · Not medical, insurance, or legal advice