There is no straight answer to this question because it all depends on your employment status. For instance, Medicare is mandatory at age 65 years, provided you are retired. However, if you are still working at this age, the size of your company will then determine whether you should sign up for Medicare or not. More specifically, if your company has less than 20 employees, then you should register for Parts A and B of Medicare insurance. On the other hand, working in a company with over 20 employees means that you probably have a substantial amount of employee group insurance, and hence, you may wait up to a later date before signing up for Medicare. Alternatively, you can register for Part A and delay other Medicare plans. Take note that late enrollment attracts penalties such as a 10% increase on your monthly premiums, according to the American Association of Retired Persons (AARP).