What Is Medicare Eligibility Date? 
You can sign up for Medicare as early as 3 months before your 65th birthday and up to 3 months after your 65th birthday . If you 're outside of this window , you will have to wait to sign up until the general enrollment period opens up for Part B -LRB- January 1-March 31 of each year -RRB- , unless you qualify for a special enrollment period . Other situations where you can be eligible for Medicare are if you 're under 65 and on social security disability -LRB- need to be on it for at least 24 months -RRB- , or have end-stage renal disease . 