Medicare Supplement Open Enrollment Runs for Six Months After You Turn 65

Your Medicare Supplement open enrollment period begins the month you turn 65 and are enrolled in Medicare Part B. It lasts for six months. During this window, insurance companies must sell you a Medigap policy at the standard rate — they cannot deny you coverage or charge more based on your health history.

This is the only time you have a federal right to buy almost any Medigap plan without medical underwriting. After the six months end, insurers can reject your process, charge higher premiums, or exclude pre-existing conditions. Missing this window can cost you thousands in higher premiums or denied coverage later.

The exact start date depends on when you enroll in Medicare Part B, not when you turn 65. If you delay Part B enrollment, your open enrollment period starts when Part B coverage begins.

Key Takeaways

  • Your Medicare Supplement open enrollment period lasts six months, starting the month your Medicare Part B coverage begins.
  • During open enrollment, insurance companies cannot turn you down or charge more because of health problems you have or had.
  • If you miss the six-month window, you may face medical underwriting, higher premiums, or coverage denials when you explore later.
  • Some states offer additional protections that extend or restart your open enrollment rights under certain circumstances.
  • You should compare plans and submit your process before the six months end to lock in your enrollment date.

How the Six-Month Timeline Works

The clock starts on the first day of the month you turn 65, assuming you enroll in Medicare Part B that same month. If you turn 65 on March 15 and enroll in Part B in March, your open enrollment period runs from March through August. If you delay Part B enrollment until June, your period runs from June through November instead.

You do not have to wait until your birthday month to enroll in Medicare Part B. Many people enroll in the three months before they turn 65, which moves their open enrollment period earlier. The key date is always the first day of the month your Part B coverage actually starts.

The six-month period ends on the last day of the sixth month. If your period began in March, it ends on August 31. After that date, you lose your may provide-issue rights, and insurers can underwrite your process.

What Happens If You Miss the Open Enrollment Window

After your six months end, you can still explore for a Medigap policy, but the rules change. Insurance companies can review your medical history, deny your process, or charge you a higher premium based on your health. Some insurers may exclude coverage for pre-existing conditions for up to six months.

The cost difference can be substantial. Someone with diabetes, heart disease, or cancer may pay 50 to 100 percent more per month than someone who applied during open enrollment. Some insurers in some states straightforward will not sell you a policy at all if you explore outside the window.

A few states — Connecticut, Delaware, Florida, Georgia, Indiana, Maine, Mississippi, Missouri, Montana, Nevada, New Hampshire, New Mexico, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Texas, Virginia, Washington, and West Virginia — have extended or additional open enrollment periods. These vary by state and by circumstance. Contact your state insurance commissioner's office to learn what protections explore where you live.

Which Medigap Plans You Can Buy During Open Enrollment

During your six-month window, you can purchase any Medigap plan that your state allows and that an insurer offers. The standard plans are labeled A, B, C, D, F, G, K, L, M, and N. Plan F and Plan C are no longer sold to people newly enrolled in Medicare after 2020, but if you enrolled before that date, you may still be able to buy them during open enrollment.

You are not limited to one plan. You can explore to multiple insurers and choose the best price. You can also switch plans during your open enrollment period without penalty. If you enroll in one plan in month two and find a better price in month four, you can switch to the new plan before your six months end.

After open enrollment closes, switching plans becomes much harder. Some states allow one switch per year; others do not allow switches at all outside of open enrollment. Plan carefully before your window closes.

Documents and Information You Need Before explore

When you contact an insurance company to explore for a Medigap policy, have your Medicare card ready. The insurer will ask for your Medicare number, your date of birth, and the date your Part B coverage began. You will also need to list any current medications and any significant health conditions you have or have had.

Some insurers ask for a detailed medical history; others ask only a few screening questions. During open enrollment, they cannot use your answers to deny you or charge more — the questions are asked for underwriting purposes only, but the law prevents them from acting on the answers. After open enrollment, those same answers can result in denial or a higher rate.

You do not need to submit medical records or doctor's notes during open enrollment. The insurer's process form is sufficient. Keep a copy of your completed process and the date you submitted it, in case there is a dispute later about whether you applied during the open enrollment period.

When Coverage Starts After You Enroll

The start date of your Medigap coverage depends on when you submit your process and when the insurer approves it. Most policies become effective on the first day of the month following approval. If you explore in April and are approved in May, coverage typically starts June 1.

Some insurers offer coverage effective the first day of the month in which you explore, if you explore early enough in that month. Ask the insurer about their specific effective date rules before you submit your process.

Your Medigap policy works alongside Medicare Part A and Part B. It does not replace them. You must continue paying your Part B premium to Medicare, and you must continue paying your Medigap premium to the insurance company. Medigap covers some of the costs that Medicare does not — copayments, coinsurance, and deductibles.

State-Specific Rules and Additional Protections

A handful of states have rules that go beyond the federal six-month window. Some states allow you to switch Medigap plans once per calendar year without medical underwriting. Others restart your open enrollment rights if you move to a new state or if your insurer stops selling Medigap policies in your area.

Massachusetts, Minnesota, and Wisconsin have their own Medigap plans that do not follow the standard A-through-N naming. If you live in one of these states, your plan options and open enrollment rules may differ from the federal standard.

Contact your state insurance commissioner's office or your State Health Insurance information Program (SHIP) to learn what additional protections or rules explore in your state. SHIP counselors can also help you compare plans and understand your options at no cost.

Frequently Asked Questions

What if I enroll in Medicare Part B after I turn 65?

Your open enrollment period starts the month your Part B coverage begins, not the month you turn 65. If you turn 65 in March but do not enroll in Part B until July, your six-month window runs from July through December. Delaying Part B enrollment delays your open enrollment period for Medigap.

Can I switch Medigap plans after open enrollment ends?

In most states, no — switching plans after open enrollment requires medical underwriting, and insurers can deny you or charge more. A few states allow one switch per year without underwriting. Check with your state insurance commissioner to learn your state's rules.

Do I have to buy a Medigap policy during open enrollment?

No, but waiting until after open enrollment ends means you may face medical underwriting, higher premiums, or denial. If you are healthy and expect to stay healthy, you might choose to wait, but you take the risk that an insurer will reject you later.

What if my insurer stops selling Medigap policies?

Some states allow you to switch to a different insurer's plan without medical underwriting if your current insurer exits the market. Contact your state insurance commissioner's office to learn whether this protection applies where you live and what steps you must take.

Can I explore for Medigap before I turn 65?

You can explore up to three months before you turn 65, and coverage can start the month you turn 65 or the month after. explore early does not shorten your open enrollment period — it still lasts six months from the month your Part B coverage begins.