Medicare supplement insurance (Medigap)

By Karen Lewis-Smith
Regional Director, Government Programs, Kaiser Foundation Health Plan of Washington

Medicare, which includes Medicare Parts A and B, provides basic, no-frills health coverage, and it leaves some gaps. That's where Medicare supplemental insurance (Medigap) comes in. To determine if Medicare supplemental insurance is right for you, consider these 7 facts.

1. A Medigap plan supplements Original Medicare, and is not an option if you have a Medicare Advantage plan. These plans are sold by private companies, and generally cover health care copayments, coinsurance, and deductibles that are not covered by Original Medicare. Some plans also provide coverage for emergency travel insurance outside the United States.

Plans sold after Jan. 1, 2006, aren't allowed to include prescription drug coverage, and most plans don’t cover long-term care, vision or dental care, hearing aids, eyeglasses, or private-duty nursing.

2. It's best to buy a Medigap plan when you first become eligible — during your Medigap open enrollment period (OEP). For Kaiser Foundation Health Plan of Washington Options, Inc. Medicare Supplement Plans, this OEP begins the first day of the month in which you are age 65 or older and enrolled in Medicare Part B. It lasts for 6 months.

For example, if your birthday is on June 5, the best time to enroll in Medigap is June 1 through Nov. 30.

During this one-time grace period, you cannot be turned down for a Medigap plan because of a pre-existing health condition, and you can't be charged more than someone who doesn't have a pre-existing condition.

After that window of opportunity closes, there's no guarantee that you'll qualify for a plan if you have health issues, and you may be charged more for a plan than if you'd purchased it during your Medigap OEP.

Notice that your Medigap OEP is different from your Initial Coverage Enrollment Period (ICEP) for Medicare, which extends from 3 months before the month of your 65th birthday to 3 months after the month of your 65th birthday.

3. You must have — and maintain — Original Medicare coverage (Medicare Parts A and B) to qualify for a Medigap plan. Medicare supplemental insurance is not an option if you have a Medicare Advantage plan. However, if you decide to switch from a Medicare Advantage plan to Original Medicare and Medigap, you can apply for your new coverage while you’re still enrolled in Medicare Advantage.

4. With Medigap coverage, you'll pay 2 monthly premiums, one for Medicare supplemental insurance and one for Medicare Part B. (There’s no premium for Medicare Part A for most beneficiaries.)

5. You can choose from Medigap Plans A, B, C, D, F, G, K, L, M, and N. (Notice that Medigap options are called "plans," while Medicare options — A, B, C, and D — are called "parts.") Plan A offers the most basic coverage, while Plan F is the most comprehensive. Medigap plans E, H, I, and J are no longer available to new subscribers.

In most states, the benefits for each level of plan are standardized by the Centers for Medicare & Medicaid Services (CMS), so you'll get the same benefits, no matter who you purchase your plan from. What differs from company to company are costs, so check those carefully.

While Medigap plans are standardized at the federal level, they are regulated at the state level, and not every plan is available in all states. In addition, Massachusetts, Minnesota, and Wisconsin have nonstandardized plans.

6. A Medigap plan covers only one person. If both you and your spouse want Medicare supplemental insurance, you'll each need to buy a policy.

7. Your Medigap plan can’t be canceled by your insurer—even if you develop health problems—as long as you pay your premium. But if you decide to drop your Medigap policy for any reason, you might not be able to get it back, or you may have to pay penalties. Before canceling your plan, be sure you fully understand the Medigap laws in your state.

For more details about Medigap plans:

    Go to and search "Medigap." You can also call 1-800-MEDICARE (1-800-633-4227) (toll free) or 1-877-486-2048 (toll free TTY for the hearing/speech impaired), 24 hours a day, 7 days a week.
  • Visit your local Social Security office1, or call Social Security at 1-800-772-1213 (toll free) or 1-800-325-0778 (toll-free TTY for the hearing/speech impaired), 7 a.m. to 7 p.m., Monday through Friday)

Learn about Medicare plans for group, state, and federal Employees

If you are becoming eligible for Medicare and your employer offers a group retiree Medicare Advantage plan through Kaiser Permanente Washington, call us at 1-800-581-8252 or TTY WA Relay 711, from 8 a.m. to 5 p.m., Monday through Friday.

PEBB and FEHB members can also find information online:

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Key Medicare enrollment dates

Medicare Annual Enrollment Period (AEP)
October 15 through December 7

Medicare Initial Coverage Election Period (ICEP)
65th birthday month + 3 months before and after

Medicare Advantage Open Enrollment Period (OEP)
January 1 through March 31


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NCQA Quality Rating

Kaiser Permanente Washington Medicare Advantage (HMO) plan was rated 5 out of 5 in the National Committee for Quality Assurance (NCQA) Medicare Health Insurance Plan Ratings 2017-2018.3