Medicare Advantage vs Original Medicare

The two paths

Almost every Medicare beneficiary lands in one of two configurations. Path one is Original Medicare (Parts A and B) plus a standalone Medigap policy plus a standalone Part D prescription drug plan. Path two is a Medicare Advantage plan (Part C) that bundles Parts A and B, and usually Part D, into a single private policy.

How each path is structured

Original Medicare is fee-for-service. You can see any provider in the country who accepts Medicare, and there are no networks or referrals. The federal program pays its share, and you owe the cost-sharing left over. Without Medigap, that cost-sharing has no annual cap. Medigap exists to cap or eliminate that exposure.

Medicare Advantage replaces Original Medicare for the enrollee. The carrier provides all Medicare-covered care, typically through a network of contracted providers, with prior authorization for many services. In exchange, plans can offer lower or zero monthly premiums, an annual out-of-pocket maximum, and extra benefits like dental, vision, hearing, and fitness memberships.

The asymmetric switching problem

The biggest factor most people miss when choosing between the two paths is that switching is not symmetric across time. Switching from Original Medicare to Medicare Advantage during the Annual Enrollment Period each year is straightforward. Switching back from Medicare Advantage to Original Medicare plus Medigap is a different story.

After your federal Medigap Open Enrollment Period has closed, federal law no longer requires Medigap carriers to issue you a policy. Whether you can buy a Medigap policy at all, and at what price, depends on the state you live in and the specific guaranteed-issue triggers that state recognizes. Some states layer on robust protections like birthday rules and anniversary rules. Others rely entirely on the federal floor and leave switching back at the discretion of carriers using medical underwriting.

How to actually decide

We do not recommend one path over the other in the abstract. The decision turns on facts that are specific to the beneficiary: current and expected health, providers you want to keep, the state you live in, your tolerance for prior authorization, your monthly premium budget, and whether you value the asymmetric switching protections that Medigap provides.

A useful frame: if you anticipate the possibility of switching plans across years, the ability to return to Original Medicare plus Medigap without medical underwriting is itself a benefit. That benefit has the most value during your federal Medigap Open Enrollment Period, when it is guaranteed at federal expense.

This article is part of a refresh queue. The current version is a port of a prior editorial and will be revised against the latest CMS publications and the structured reference cards on this site.