Three months out: the window opens
Your Initial Enrollment Period spans seven months centered on your birthday month. Enrolling in the first three months means coverage starts the month you turn 65, with no gap.
Already drawing Social Security? Parts A and B usually start automatically and your card arrives in the mail. Everyone else enrolls at ssa.gov, by phone, or at a local office.
The one decision that forks: still working?
Employer coverage from active employment (yours or your spouse’s, generally at companies with 20 or more employees) lets you delay Part B without penalty. Smaller employer or retiree coverage usually does not. Getting this call wrong creates lifetime penalties, so verify with the benefits office in writing.
Choose your path, then your plan
Decide the structure first: Original Medicare plus Supplement plus drug plan, or an all-in-one Advantage plan. Then pick the specific plan against your doctors and prescriptions. Your six-month Medigap open enrollment starts with Part B, and it is the one window where no insurer can turn you down.
What can wait, and what cannot
Dental add-ons, hospital indemnity and fine-tuning can happen after the dust settles. Parts A, B and D deadlines cannot. When in doubt, one call to an independent agent sequences all of it for you, free.