The 6-month Medigap open enrollment period is a one-time window during which insurance companies must sell you any Medigap (Medicare Supplement) policy they offer, regardless of your health status. It begins the month you turn 65 and are enrolled in Medicare Part B, and it lasts exactly six months. Once it closes, you may never get these same protections again under federal law.
When the Window Opens and Closes
Your Medigap open enrollment period starts on the first day of the month you are both 65 or older and enrolled in Medicare Part B. For most people, that means it begins the month they turn 65, since many enroll in Part B at that time. If you delay Part B enrollment (because you’re still working with employer coverage, for example), your open enrollment period starts when Part B kicks in, even if that’s after your 65th birthday.
From that start date, you have exactly six months. There is no extension, no grace period, and no way to restart the clock. If your Part B effective date is July 1, your Medigap open enrollment runs from July 1 through December 31.
What This Period Protects You From
During these six months, insurance companies cannot use medical underwriting against you. That means they cannot deny your application because of a health condition, charge you a higher premium based on your medical history, or refuse to sell you any standardized Medigap plan (A through N) that they offer in your state. Every plan with the same letter covers the same benefits no matter which company sells it, so you’re free to shop purely on price and company reputation.
Outside of this window, insurers in most states can review your health history before deciding whether to sell you a policy and at what price. If you have diabetes, heart disease, or another chronic condition, you could be denied outright or quoted a significantly higher premium. That’s what makes this six-month period so valuable: it’s the broadest set of consumer protections you’ll get under federal law.
Pre-existing Conditions During Open Enrollment
Even during the open enrollment period, insurers can impose a waiting period of up to six months before they cover treatment related to a pre-existing condition. A pre-existing condition is any health issue that was diagnosed or treated in the six months before your Medigap policy starts.
However, prior creditable coverage (such as employer insurance, COBRA, or a Medicare Advantage plan) shortens that waiting period month for month. If you had creditable coverage for two months, the insurer can only impose a four-month wait instead of six. If you had six or more months of continuous creditable coverage, the insurer must cover your pre-existing conditions immediately with no waiting period at all. One important catch: a break in creditable coverage of more than 63 days resets this credit, so keeping continuous coverage matters.
Why Pricing Method Matters at 65
Medigap insurers use one of three pricing structures, and understanding them helps you evaluate quotes during your open enrollment window.
- Community-rated: Everyone pays the same premium regardless of age. These policies tend to cost more at 65 but become a better deal over time because your rate doesn’t climb as you age.
- Issue-age-rated: Your premium is based on your age when you first buy the policy. It won’t rise because of your birthday, though it may still increase with inflation or other factors. These cost more than attained-age policies at 65 because they build in the expectation that your healthcare needs will grow.
- Attained-age-rated: Your premium is based on your current age and rises as you get older. These are the cheapest option at 65 but become progressively more expensive. By age 75, attained-age premiums can surpass community-rated premiums, and by 85 the gap can be hundreds of dollars per year.
Because the same lettered plan offers identical benefits regardless of company, price and pricing method are the real decisions during open enrollment. Contacting multiple insurers for quotes is worth the effort, since costs vary widely for the exact same coverage.
If You’re Under 65 on Medicare
People who qualify for Medicare before 65 due to a disability or end-stage renal disease do not automatically get a federal Medigap open enrollment period. Federal law does not require insurers to sell Medigap policies to anyone under 65. Some states have their own laws that create open enrollment rights for younger Medicare beneficiaries, but protections vary significantly. If you’re under 65, checking with your State Insurance Department is essential to know what options exist where you live.
What Happens After It Expires
Once your six-month window closes, buying a Medigap policy becomes harder and potentially more expensive. Insurers can use medical underwriting, meaning they review your health history and can deny coverage or charge more. There are limited exceptions called guaranteed issue rights, which apply in specific situations like losing employer coverage or having a Medicare Advantage plan leave your area.
One notable exception involves trying Medicare Advantage for the first time. If you drop a Medigap policy to join a Medicare Advantage plan and decide within 12 months that it’s not for you, you have a trial right to return to your old Medigap policy (if the same insurer still sells it) without underwriting. Similarly, if you joined Medicare Advantage when you first became eligible at 65 and switch back to Original Medicare within the first year, you can buy certain Medigap policies with guaranteed issue protections.
How to Apply During Open Enrollment
The process is straightforward. First, decide which lettered plan fits your needs by comparing the standardized benefits. Then shop across multiple insurance companies in your state for that same plan letter, since benefits are identical but premiums can differ substantially. Your state may have a Medigap rate comparison guide available through its State Health Insurance Assistance Program (SHIP), which offers free counseling.
When you’re ready, contact the insurer directly, request a formal quote, and fill out the application. During open enrollment, you won’t need to provide medical records or proof of health. If you’re applying outside of open enrollment under a guaranteed issue right, you’ll typically need documentation such as letters or notices proving your eligibility. The insurer must provide a clearly worded summary of the policy before you finalize, so read it carefully and ask questions about anything unclear.