California Medicare Supplement Birthday Rule 2027: How the 60-Day Window Works

Reviewed by Russell Noga, Licensed Medicare Insurance Broker (all 50 states) — Last updated October 27, 2026

Most people only get one easy shot at a Medigap policy: the six months after Part B starts. After that, a new company in most states can ask about your health and turn you down. California is different. State law gives every Medigap policyholder a fresh switching window each year, tied to the one date nobody forgets.

Below we walk through what the law actually says, which plan changes it allows, a full set of dates for a 2027 birthday and how California’s window stacks up against the other states that copied the idea.

The rule lives in California Insurance Code §10192.11(h). In plain terms, it gives you four things:

California first passed a birthday rule in 1997 with a 30-day window. Senate Bill 407, signed October 7, 2019, stretched it to 60 days starting in 2020. Insurers that are licensed by the Department of Managed Health Care follow a matching rule in the Health and Safety Code.

The law compares benefits, not prices or company names. Using today’s standardized plan letters, the common moves look like this:

Thinking through a letter change? Our guides on switching from Plan F to Plan G and moving from Plan N to Plan G cover the cost side.

Here’s how the calendar works for a California Plan G holder whose birthday is March 14, 2027 and who wants the same plan from a company with a lower premium. Counting your birthday as day one, a 60-day window runs through May 12.

The Medicare Advantage limit catches people out. The health-question ban only applies while you’re covered by another Medicare Supplement policy, so a Medicare Advantage member can’t use their birthday to buy back in. California has separate guaranteed issue rights when a Medicare Advantage plan ends or leaves your area, and the federal Medigap trial right covers some first-time Medicare Advantage members. If you’re weighing that move, read switching from a Medicare Supplement to Medicare Advantage first.

California’s rule was an early model. We pulled the details below from the NAIC’s state-by-state chart of filed laws, dated May 11, 2026. Only California, Idaho, Nevada and New Mexico combine a window of about two months with freedom to change companies and plan letters.

Delaware, Oklahoma, Wyoming and West Virginia have their own versions, and Virginia and Indiana let you buy the same plan from another company. Laws change often, so check with your state insurance department before relying on any row.

Since the benefits of a given plan letter are identical at every company, the only question is price, both today and over the next few years. A few things are worth checking before your window opens:

You can apply for a different Medigap policy any day of the year. The catch is that outside the birthday window, and outside your first Medicare Supplement open enrollment period, the company can review your health and decline you. That’s when you’d see the Medigap underwriting questions about recent hospital stays, diagnoses and prescriptions.

Federal guaranteed issue rights, such as losing employer retiree coverage, work separately from the birthday rule. Our comparison of Medicare Supplement open enrollment vs. guaranteed issue explains which one applies to you.

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