If you’ve had an insurance plan through your employer for most of your life, you’re probably accustomed to annual open enrollment, where you can easily switch insurance plans after comparing coverage and premiums.
Once you turn 65 and opt into Medicare coverage, however, open enrollment opportunities for supplemental coverage are few and far between. In the case of Medigap, a supplemental insurance plan for Medicare, that opportunity only occurs once per lifetime without requiring medical underwriting.
The exception to this falls under the Medigap “birthday rule.” Read on to learn more about what the birthday rule is and how it works.
[Read: How to Choose a Medicare Plan: 5 Essential Steps]
What Is the Medigap Birthday Rule?
The Medigap birthday rule establishes additional open enrollment periods so Medigap open enrollment is no longer a once-in-a-lifetime event. To qualify for the birthday rule, you need to already carry a Medigap plan. The birthday rule is only to switch Medigap plans, which include plans A, B, C, D, F, G, K, L M and N, but doesn’t apply if you never carried a Medigap plan to begin with.
Jessica Topolski, a Medicare specialist at AZ Health Insurance Brokers in Phoenix, gives the following example:
Say you’re currently enrolled in Medigap Plan G, but you want to change to a less expensive plan, like Plan N. When your birthday comes around, depending on which state you live in, you’ll have an allotted time to switch your plan.
“It’s similar to the open enrollment period they had when they first were eligible for Medicare,” Topolski says.
[Read: Medigap Plans F, G and N Compared: 2026 Costs and Selection Guide]
As of July 2026, 15 states have enacted some type of Medigap birthday rule: California, Delaware, Idaho, Illinois, Indiana, Kentucky, Louisiana, Maryland, Nevada, Oklahoma, Oregon, Utah, Virginia, West Virginia and Wyoming. New Mexico will introduce the Medigap birthday rule in 2027.
The Medigap birthday rule or open enrollment periods are subject to change or be initiated through state-specific legislative action like state Senate bills. There are currently no federal regulations for the birthday rule.
[Read: What’s the Difference Between Medicare and Medigap?]
How State Birthday Rules Differ
Since the Medigap birthday rule is state-specific, there are variations between each state regarding:
— State availability: Which states offer the birthday rule at all
— Enrollment window duration: How long the window is for enrollment changes. For example, the window in Idaho is 63 days after your birthday, while the window in Maryland is 30 days. In some states, such as Oregon, the window starts before your birthday.
— Carrier portability: Whether the change in plan needs to be with the same insurance carrier or if you can switch carriers
— Benefit tier limits: Whether the change must be to a policy with equal or lesser coverage
— Cost-sharing obligations: Whether the new plan incurs more or less cost-sharing responsibilities, like coinsurance
— Age restrictions: How old you can be. For example, Illinois only allows the birthday rule up to and including age 75.
Some states offer year-round open enrollment, like Connecticut, New York, Vermont and Washington state. Each of these states has specific requirements for eligibility to make a plan switch.
Comparative overview of state birthday rules
Examples of the differences in Medigap birthday rule enrollment by state include:
| State | Window Duration | Plan Tier and Carrier Rules |
| California and Nevada | 60 days starting on your birthday | Equal or lesser benefits; any participating carrier |
| Oregon | 61 days (the window begins 30 days prior to your birthday) | Equal or lesser benefits; any participating carrier |
| Idaho | 63 days | Equal or lesser benefits; any participating carrier |
| Delaware and Indiana | 30 to 60 days surrounding your birthday | Delaware allows equal or lesser benefits. Indiana limits to the same plan letter. |
| Illinois and Louisiana | 45 days (Illinois) to 63 days (Louisiana) from your birthday | Equal or lesser benefits; limited to plans with your current insurer or an affiliate |
Source: Medicareresources.org
Guaranteed Issue Rights vs. Medical Underwriting
The Medigap birthday rule gives you what’s known as “guaranteed issue rights,” which means you won’t face a process known as “medical underwriting” when applying for a new plan. Understanding these two concepts is key to ensuring you’re getting the Medigap plan you need.
What is a guaranteed issue right?
A guaranteed issue right, also known as “Medigap protections,” means an insurance company cannot deny you a Medigap policy or charge you higher premiums for a preexisting condition, such as diabetes or heart failure. It’s enacted when you first sign up for Medigap, meaning you are in your open enrollment period, or in certain situations where your health coverage changes outside of open enrollment.
With guaranteed issue rights, there are no medical questions, and the member selects their desired plan and is enrolled, says Dominic Morrone, the principal president of the ABC Unit of World Insurance Associates LLC in Blackwood, New Jersey.
In contrast, if you want to switch Medigap plans outside of open enrollment, guaranteed issue rights typically do not apply and insurance companies can deny your coverage, limit your plan options or charge more for your plan, all of which fall under the umbrella of “medical underwriting.”
What is medical underwriting?
Medical underwriting is a risk assessment for insurance carriers to determine if they want to provide you with a Medigap plan. This may entail:
— Completing a comprehensive health assessment
— Answering questions about your health
— Providing medical records at the request of the underwriter
Underwriting requirements for Medigap plans may also differ by state. Insurance companies can deny you a policy or charge more for a policy as a result of the medical underwriting process.
Medigap Refresher
For new Medicare enrollees just learning the ins and outs of the complex health insurance system, Medigap is supplemental insurance to original Medicare that helps cover some of the out-of-pocket costs associated with Medicare coverage. Medigap plans are sold by private insurance companies, not by the federal government, though they are overseen by the Centers for Medicare & Medicaid Services.
How the supplement works with the parts of Medicare:
— Part A (hospital insurance) and Part B (medical insurance): Medigap helps supplement Medicare Part A and Part B. To hold a Medigap policy, you must also have Medicare parts A and B coverage. Your eligibility for a Medigap plan begins after you enroll in Medicare Part B.
— Part C (Medicare Advantage): Medicare Advantage plans are an alternate to original Medicare. These plans, sold by private insurance companies, offer comparable coverage to original Medicare as well as extra perks, such as dental and vision coverage, and a maximum out-of-pocket limit.
— Part D (drug coverage): Part D is separate from Medigap coverage. Medigap doesn’t cover Part D, and you can choose to opt in or out of Part D with no effect on your Medigap plan.
According to CMS, other supplemental plans that aren’t Medigap include:
— Medicaid
— Employer plans or COBRA coverage
There are a variety of Medigap plans to choose from that offer standardized coverage. In other words, Medigap Plan A at Company X will have the same benefits as Medigap Plan A at Company Z. The only differences between the plans is the cost, as they are sold by private insurance companies who select their pricing.
What does vary under each Medigap plan, however, are the benefits, including:
— Coinsurance and copayment coverage
— Deductibles
— Skilled nursing care benefits
— Blood transfusion coverage
— Foreign travel benefits
— Out-of-pocket limits
Plan A, for instance, doesn’t offer the same benefits as Plan K. For a complete chart of these benefit comparisons, visit Medicare.gov.
Medigap policies also have an initial open enrollment period similar to original Medicare. Traditionally, Medigap plan open enrollment only occurs once per lifetime, under the following conditions:
— You are at least 65 years old.
— You are enrolled in Medicare Part B.
— You have a Medicare number.
— No more than six months have elapsed since your Medicare Part B coverage began.
If you qualify for Medicare for a certain disability, like end-stage renal disease, but you’re under 65, you’ll need to check with your state of residence to see if you’re eligible for Medigap coverage.
The Bottom Line
The Medigap birthday rule provides additional open enrollment periods throughout your lifetime to switch Medigap plans. Medigap birthday rules are state-specific, so check with your state’s Department of Insurance or State Health Insurance Assistance Programs for assistance or more information.
“I believe the birthday rule is a step in the right direction,” Morrone says, referring to giving consumers more freedom with their healthcare coverage options. He believes other states will probably be adding the birthday rule to provide consumers with more healthcare choices.
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What Is the Medigap Birthday Rule and Which States Have It? originally appeared on usnews.com
Update 07/28/26: This story was published at an earlier date and has been updated with new information.
