Guide to 2021 Medicare Enrollment and Best Insurance Companies

Annual Enrollment Period for Medicare Advantage and Medicare Prescription Drug coverage starts on Oct. 15.

Through Dec. 7, Medicare beneficiaries can shop for new health insurance plans or change their existing plans. At the start of annual enrollment, the Centers for Medicare & Medicaid Services releases star ratings for thousands of health insurance plans across the nation.

Find out everything you need to know about how to buy a health insurance plan during annual open enrollment, from the insurance companies top-rated by U.S. News in your state to the difference between a Medicare Advantage and Medicare Supplement plan.

Best Insurance Companies

Every year, U.S. News rates insurance companies across the country in order to help consumers find the best Medicare plans in their state. The methodology didn't change in 2021 -- but the winners did. Companies that consistently offer highly rated Medicare Advantage plans in multiple states include Cigna, Essence Healthcare, HealthPartners, HealthPartners UnityPoint Health, Kaiser Permanente, Martin's Point Generations Advantage, Providence Medicare Advantage Plans, Quartz Medicare Advantage and UnitedHealthcare. For Part D Prescription Drug plans, 11 states have one insurer that made the U.S. News list, with a Blue Cross Blue Shield company being that insurer in all 11 states.

Learn more about 2021's new ratings (and best insurance companies) here.

What is Medicare Advantage?

Medicare Advantage plans offer an alternative to original Medicare, in which health coverage is 100% provided by the government. Such plans offer a broad range of private health insurance plans with coverage that meets requirements set by Medicare, including basic hospital and health coverage that reflects Medicare Part A and B services.

Most Medicare Advantage plans offer prescription drug coverage, and some offer additional dental and vision coverage. The steps to choosing a plan during annual open enrollment are layered and include questions like whether or not you want to cap out-of-pocket health spending. (Original Medicare does not offer out-of-pocket maximums.)

Cost comparison

Why change your Medicare plan? During Medicare's annual open enrollment period, you don't have to ditch your current Medicare plan in order to experience added benefits or more affordable coverage -- consumers have the option to modify their existing plan, as well.

During this period, consumers can:

-- Add Medicare Part D prescription drug coverage to their plans.

-- Buy supplement insurance and switch to another Medicare Advantage plan.

-- Opt out entirely.

Changes made during annual open enrollment take effect Jan. 1 of the following year.

Choosing supplement insurance

Once you've enrolled in a Medicare plan with dual hospital and health coverage (otherwise known as Medicare Part A and B insurance), you can consider opting for Medicare Supplement insurance, as well. Supplement plans offer to cover the "gaps" in traditional Medicare plans (hence its alternate title, Medigap insurance), including coinsurance at skilled nursing facilities and copayments for primary care visits.

The most comprehensive Medigap option that beneficiaries can choose is Plan F. However, Plan F is not available to people new to Medicare starting on January 1, 2020, because it covers the Part B deductible. Individuals who were eligible for Medicare before January 1, 2020, but not yet enrolled, may be able to buy Plan F. Medigap enrollees can continue renewing their plan as long as they pay their monthly premium.