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Do Medicare Parts A, B Backup My Medicare Advantage Plan?
Ask Rusty – Social Security Matters 2-23-22

Dear Rusty: I was told that I can use Medicare Parts A and B as secondary coverage to my Medicare Advantage plan. Is that true? Signed: Puzzled


Dear Puzzled: Many do not understand how the various parts of Medicare work, and especially how or if “original Medicare” (Medicare Part A and Part B) interacts with a Medicare Advantage plan. If you now have a Medicare Advantage plan, it is the private insurer who provides your plan that administers all of your healthcare needs, instead of the federal government agency which runs Medicare (that federal agency is called the Centers for Medicare & Medicaid Services, or “CMS”).

Although you must pay Medicare Part A and Part B premiums to the federal government to obtain a Medicare Advantage plan, all your healthcare services are handled by the private Medicare Advantage plan provider and not by the government’s CMS agency. When you have an Advantage plan, Medicare Parts A and Part B do not act as secondary coverage for your Advantage plan. You don’t get healthcare services from both, because when you choose a Medicare Advantage plan you are deselecting CMS as the administrator of your healthcare needs.

Deciding whether to use “original Medicare” to administer your healthcare services or to use a Medicare Advantage plan is always a very personal choice. Medicare Advantage plans cover almost all the medically necessary services that original Medicare covers, although you must generally use “in-network” providers to obtain full coverage. But if you incur healthcare expenses which are not covered by your Medicare Advantage plan, you must pay them yourself – federal Medicare Parts A and Part B are not backup coverage for those uncovered healthcare expenses. So, what you were told is incorrect – Medicare Part A and Part B do not act as secondary coverage to your Medicare Advantage plan.


This article is intended for informational purposes only and does not represent legal or financial guidance. The opinions and interpretations expressed in this article are the viewpoints of the Association of Mature American Citizens Foundation’s Social Security Advisory staff. To submit a question, visit their website ( or email them at