A 72-year-old Medigap Plan G enrollee faces a 14% premium hike but can use California's annual birthday rule to switch plans without medical underwriting. Fifteen states plus Missouri offer similar guaranteed-issue windows tied to birthdays or enrollment anniversaries, allowing moves to equal or lesser plans. These rules help avoid premium lock-in due to health issues. Medicare Advantage enrollees and drug plans are excluded. Applications must be timely and within state-specific windows.