Open enrollment is the yearly period when you can sign up for, switch, or drop a health plan without needing a qualifying life event. Employers run their own windows, usually in the fall for a January 1 start; the federal and state marketplaces and Medicare each have their own dates. Outside the window, changes are generally limited to special enrollment periods triggered by events like a job change, marriage, or a move.
For anyone on or considering a GLP-1, this is the one moment each year when plan choice is in your hands. It's worth pulling each plan's formulary and checking whether the specific drug is listed, at what tier, and with what prior authorization or step-therapy requirements — coverage can differ sharply between plans from the same employer. It's also the deadline employers work toward when deciding whether to add GLP-1 coverage, so requests to HR land best several months earlier. See how to determine if your formulary covers GLP-1 medications and how employer self-funded plans decide GLP-1 coverage.
For HealthCare.gov Marketplace plans, the window runs November 1 to January 15 (HealthCare.gov (external link)).