Short answer: For ESRD, Medicare usually starts the first day of the fourth month of dialysis (the first month if the person does home dialysis training), or the month of admission for a kidney transplant; it ends 12 months after dialysis stops or 36 months after a successful transplant if ESRD is the only basis.
Eligibility applies at any age if the person (or a spouse or parent) has enough Social Security, Railroad Retirement or government work, or gets those benefits. Signing up is optional, but Parts A and B are both needed for full dialysis and transplant coverage. Coverage can be retroactive up to 12 months before the month of application, and enrolling based on ESRD carries no Part B late penalty.
Transplant timing: Medicare can begin the month of admission if the transplant happens that month or within the next 2 months; if delayed longer, coverage begins 2 months before the transplant month. Coverage resumes right away if dialysis restarts or another transplant occurs.
After a transplant, people who lose Medicare at 36 months can buy the Part B immunosuppressive drug benefit: for 2026, $121.60 per month (more with higher income) and a $283 deductible, then 20 percent.