What Is the Medigap Birthday Rule and Which States Have It?

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 …