What Do I Need To Know About Medicare Open Enrollment? 
Your Medicare Supplement open enrollment is actually a one-time 6-month period that starts the first month that you are age 65 -LRB- or older -RRB- AND enrolled in Medicare Part B . This period gives you guaranteed issue rights to buy any Medicare Supplement policy in your area with no health restrictions . The Medicare Advantage -LRB- Part C -RRB- and Medicare Drug Plans -LRB- Part D -RRB- have an annual open enrollment that starts October 1st each year . With this open enrollment period you can compare plans beginning on October 1st . You can make changes beginning on October 15th and ending on December 7th . The plan changes take effect on January 1st . 