when must i enroll in medicare?

Three months prior to your 65th Birthday. I just recently enrolled and went for just the Medicare Part A and B. There are other options through various insurance companies (who will contact you relentlessly prior to your 65th). If you do take quite a few med's you should consider Part D for a discount on your RX's. The cost (presently) for Part B is $134 a month (Part A is at no cost). Part B is for Dr. vists / Part A for hospitalization / outpatient clinics.

If you don't enroll in part B when you're first eligible and join later, you have to prove creditable coverage or you get penalized. Also, if you have an insurance through work and Medicare is primary due to reasons like retiree or Cobra status, they can estimate part B payments and pay hardly anything on services covered by part B like Drs visits, medical supplies and testing. So if you're using a group plan instead of getting part B you can call them and ask who'd be primary if you got Medicare.

I don't think anyone is required to. I got it at 21. Age can vary. I'm sorry if I offended anyone. I strive to answer all questions sincerely and with true information.

You should enroll a few months before you turn 65 unless you're permanently disabled.