Q: My dilemma has to do with when you should enroll in Medicare. My friends each have their own interpretation of when you must enroll. Some say at age 65, others say when you reach full retirement age, and others say you don't have to sign up as long as you continue to work. Is there a right answer?

A: Let me assure you that this particular question causes a dilemma for many, and friends and relatives mean well when they answer your questions based on when they enrolled in Medicare.

To address your question — "Is there a right answer?" — the answer is there is no "one" right answer because when you should enroll in Medicare depends on each person's unique situation.

Currently, there are four parts to Medicare coverage. Medicare Part A is your hospital insurance; Medicare Part B is your coverage for medical expenses; Medicare Part C covers Senior Advantage Plans, i.e., HMOs, PPOs etc.; and Medicare Part D covers prescription drugs.

For ease of answering your question, I am not going to address Part C, Senior Advantage Plans, in this column. I will leave that subject for another day.

If you are already getting benefits from Social Security or the Railroad Retirement Board, you will automatically be enrolled in Part A starting the first day of the month in which you turn 65.

If you are close to 65 and have not yet started collecting Social Security or Railroad Retirement benefits you must apply for Part A and should do so at age 65. You may make an application up to three months before your 65th birthday.

For most people, there is no monthly premium for Medicare Part A because they or their spouses paid Medicare taxes while working.

The second part of Medicare is Part B. This is your medical insurance and helps cover your doctor's service and outpatient care. It can also help to pay for physical and occupational therapists and some home healthcare when medically necessary. There is a monthly premium for Medicare Part B coverage.

Again, if you are receiving Social Security or Railroad Retirement benefits before turning 65 you are automatically enrolled in Part B starting the first day of the month in which you turn 65.

There are three times when you can sign up for Medicare Part B if you are not automatically enrolled. They are the initial enrollment period, the special enrollment period and the general enrollment period.

The initial enrollment period starts three months before you turn 65 and ends three months after the month in which you turn 65. Even though the eligibility age to receive full Social Security or Railroad Retirement benefits now depends on the year you were born, it doesn't affect Medicare eligibility, which remains at 65.

The special enrollment period is available if you waited beyond 65 to enroll in Medicare Part B because you or your spouse were working and had group health insurance coverage through your employer or union based on current employment.

If your employer or union has more than 20 employeesormembers, you do not have to sign up for Medicare Part B until you either stop working or your employer or union stops such coverage, whichever comes first. When that coverage stops you have eight months in which to enroll in Medicare Part B without incurring any penalties for late enrollment.

The third opportunity you have to sign up for Medicare Part B is the general enrollment period. The general enrollment period runs from Jan. 1 through March 31 of each year with an effective coverage date of July 1. This enrollment period is available for those who did not sign up for Part B when they first became eligible for that coverage.

Enrollment in Medicare Part D, Prescription Drug Coverage, generally follows the same rules as described for Part B. You should sign up for Part D at age 65 unless you have other prescription coverage that is at least equal to or better than the coverage offered through the Medicare plans.

Hope that helps you to understand the complexity of Medicare enrollment.

— Betty Berry is a senior advocate for Senior Concerns. The advocates are at the Goebel Senior Adult Center, 1385 E. Janss Road, Thousand Oaks, CA 91362; or call 495-6250. You are invited to submit questions on senior issues.