Most states let a Medigap carrier underwrite you once your initial six month open enrollment has passed, which means a health condition can lock you into whatever policy you already hold. Idaho is one of a small group of states that carved out an exception.
What the rule allows. Once a year, in the window tied to your birthday, you may move to a different Medigap policy of equal or lesser benefit value without medical underwriting. You keep your existing coverage type or step down, and the new carrier cannot decline you or rate you up for health reasons.
What it does not allow. It is not a path to upgrade. You cannot use the birthday rule to move from a lesser plan to a richer one, and it does not apply to moving between Medicare Advantage and Medigap. It is Medigap to Medigap only.
Why it matters in practice. Medigap premiums for the same standardized plan can differ meaningfully between carriers, and those differences grow as rates increase over time. Because Plan G from one carrier covers exactly what Plan G from another covers, the birthday rule effectively lets Idahoans re-shop price each year without risking their coverage. Reviewing it annually is one of the few genuinely free wins in Medicare.
Before you switch. Confirm the exact dates of your window, make sure the new policy is issued before you cancel the old one, and check the new carrier’s rate history rather than just its first year price. Idaho’s Department of Insurance can confirm current rule details, and we will check them with you at no cost before you switch.
Related on this site: Medicare Supplement (Medigap) plans · Plan G vs Plan N in Idaho
Sources
- Idaho Department of Insurance · accessed September 14, 2026
- How to compare Medigap policies (CMS) · accessed September 14, 2026
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