When Can I Enroll In Part B Medicare? 
You can enroll in Medicare Part B when you turn 65 , when you have a special enrollment period -LRB- e.g. you 're 65 or older and coming off of group coverage -RRB- , or during the general enrollment period -LRB- January 1-March 31 of each year -RRB- . You may also be eligible for Part B under age 65 if you 're on social security disability or have a specific medical condition -LRB- e.g. ESRD or ALS -RRB- and meet eligibility requirements . When enrolling under a special enrollment period , the effective date would be the 1st of the following month after you apply . The effective date of coverage when applying during the general enrollment period will be July 1 of the year you apply . Please note , if you do n't enroll in Part B when you 're first eligible and you do n't have a special enrollment period available to you , you may be subject to a late enrollment penalty -LRB- premium can go up 10 % for each full 12-month period that you could have enrolled in Part B , but did not -RRB- . When you enroll in Part B , you also activate your 6-month open enrollment period to purchase a Medigap plan to cover the gaps in original Medicare -LRB- Parts A & B -RRB- with NO MEDICAL UNDERWRITING ! This is the best time to buy one if you do n't want to create an extremely predictable healthcare expense structure . Please feel free to contact me for further assistance . Thanks very much . 