Medicare has specific enrollment periods around your 65th birthday. Social Security beneficiaries are automatically enrolled in Parts A and B. It's important to act within these timelines to avoid penalties. Medicare costs include premiums and deductibles, but assistance programs are available for those with low income. Different plan options include Original Medicare, Medicare Advantage (Part C), Medigap plans, and Part D for prescriptions. Annual evaluations during open enrollment help select the best plan for changing health and financial needs.