Original Medicare and Medicare Supplement (Medigap) Work Together
If you have Original Medicare and a Medicare Supplement (Medigap) policy, Medicare will pay its share of the Medicare approved amounts for covered health care costs, then your Medigap policy will pay its share.
In Maine, and most other states, Medigap insurance is only sold as a "standardized" plan, identified by the letters A through N. Each standardized policy must offer the same benefits. In other words, a Plan A sold by one company will have the same benefits as a Plan A sold by another company. Cost is the only difference between policies with the same letter sold by different companies.
You can see what each of the standardized policies covers by viewing the Standardized Policies Chart on page 8 and a description of plan benefits and deductibles on page 6 of the Consumer Guide to Medicare Supplement (PDF).
Limitations on Switching Plans
When you buy your plan, keep in mind that in the future your ability to switch plans will be limited by what you purchase now. If you buy a lower benefit Medicare supplement plan, you may not be able to enroll in a higher benefit plan later. On page 5 of the Consumer Guide to Medicare Supplement (PDF) you can see which plans you can switch to later, based on your current plan.
In Maine, you have the right to change Medicare supplement plans as long as you change to a plan with the same benefits or a plan with lesser benefits, and you have never had a gap in coverage that supplements Medicare of more than 90 days since your Open Enrollment Period.