En español | Q. I'll be 65 in July. I've always assumed that I need to sign up for Social Security and Medicare when I reach that birthday. Is that correct?

A. Well, yes and no. When you turn 65, you'll probably need to sign up for Medicare. But when it comes to Social Security, you don't have to do anything now. You can apply for retirement benefits anytime between now and age 70, with your monthly check rising the longer you wait. Your benefits generally will begin about three months after you apply.

See also: Will getting a pension lower my benefit?

Medicare has a seven-month period in which you can sign up for Part B, which covers doctor bills and other outpatient medical costs. This period begins three months before the month of your 65th birthday, includes the month you turn 65 and ends three months after your birthday month.

It's a good idea to apply at the start of that period. If you dither and miss the deadline, your monthly premium will probably be 10 percent higher — for the rest of your life — for each 12-month period you were eligible but did not enroll.

However, there's an important exception to this rule. If when you turn 65 you're still working and have health insurance from your employer or through your spouse's employer, Medicare may permit you to postpone, without penalty, the date when you have to enroll.

Generally speaking, that exception period ends when you stop working and no longer have job-based health care coverage.

For more information on how to qualify for that exception, called a special enrollment period (SEP), see this Medicare publication.

Q. I'll soon be 66 years old, my full retirement age, and I plan to apply for my retirement benefits. I'm currently working full time and intend to continue at it until my 70th birthday. My question is: After my 66th, can I draw Social Security and continue to work full-time without giving back any of my benefits?

A. Yes, you can. You're apparently concerned about the Social Security earnings limit. But you need not worry. The limit applies only to workers receiving benefits between age 62 and full retirement age.

For the years before the one in which you turn 66, you're allowed to earn up to a ceiling, $14,640 a year for 2012, before Social Security begins to withhold some or all of your benefits. There's another ceiling, currently $38,880, that applies just to the year in which you reach full retirement age.

After that key birthday, the limit goes away and you are free to earn as much as you like — without penalty. For more information on the earnings limit and just how much could be deducted from your check, see this Social Security webpage.

You may also like: The impact of claiming age on monthly benefits.

Stan Hinden, a former columnist for the Washington Post, wrote How to Retire Happy: The 12 Most Important Decisions You Must Make Before You Retire. Have a question for the Social Security Mailbox? Check out the archive. If you don't find your answer there, send a query.