If you are meet the requirements for premium-free Medicare Part A and you were not automatically enrolled in the program, then you should sign up when you first meet requirements. However, you may decide to delay enrollment if you have insurance through your employer. 

Keep in mind, though, that delaying enrollment may require you to pay a penalty later on unless you are exempted from this rule. This penalty typically increases the longer you put off enrollment.

For example, you will not have to pay a late enrollment fee if you are (or your spouse is) working and have group health insurance through the employer.

In this case, you may also qualify for a special enrollment period if those things are true. 

A special enrollment period is when you can sign up for Medicare after your initial period without waiting for the open or general enrollment periods.

Your special enrollment period is 8 months and starts (whichever comes first):

• The month after the employment ends, whether you or your spouse’s.
• The month after the group health insurance plan coverage ends. 

If you do not qualify for a special enrollment period and have missed your initial period, you will need to wait for one of the open enrollment periods. 

Remember that whether you qualify for Medicare because you have turned 65 years of age or health condition, you must meet the other basic requirements before you can enroll. This includes being a United States citizen or a qualifying non-citizen.

Even if you are older than 65, you cannot sign up if you do not meet the basic citizenship requirements.