Q. Someone told me if you don’t sign up for Social Security as soon as you are eligible, but do sign up a few years later, you get back pay to when you were first eligible. Is this true?

A. In general, Social Security benefits cannot be paid retroactively to the month the application for benefits is filed. The exception is if the applicant is past full retirement age. In that case, up to six months of retroactive benefits can be paid as long as backdating the application does not result in benefits being paid for any month prior to full retirement age.

Q. I have been of the belief that Social Security benefits are determined by taking the average income of all the years of employment. I recently heard that it is the average of the highest 35 years of employment. Which is correct?

A. Monthly Social Security benefits are determined on average monthly earnings over 35 years. When a benefit application is filed, the Social Security Administration indexes lifetime earnings to bring them up to date. The highest 35 years of earnings are selected and averaged to determine the monthly benefit. If a worker has more than 35 years of earnings, excess lower-earning years are disregarded. If the worker has fewer than 35 years of earnings, some zero income years are included in the calculation.

Q. If I were to retire at age 60 and begin receiving Social Security benefits at age 62, would the two years of zero earnings between my retirement and beginning to collect benefits be factored into my Social Security benefit calculation? If so, would this greatly reduce my benefits?

A. How leaving the work force before retirement age or changing to new, lower wage employment will affect your monthly Social Security benefit depends on your prior earnings history. If you have spent your full work life in the paid work force, a minimal number of low or no-earning years could make very little difference in the amount of your benefit. If you have a short earnings history, the difference could be substantial.

The best way to learn how leaving the work force early or accepting a lower paying job would change your latest benefit estimate is to use the online estimator. Go to http://www.socialsecurity.gov/estimator/. More detailed calculators can be found at http://www.socialsecurity.gov/planners/benefitcalculators.htm.

Q. A Federal retiree who is not eligible for Social Security has elected a 100 percent survivor annuity for his spouse. His wife is eligible for Social Security benefits based on her own work history. When he dies, does she collect the full 100 percent spousal survivor annuity plus her own Social Security or is her Social Security or survivor annuity reduced?

A. Receipt of a Federal Civil Service Survivor Annuity never affects a widow’s own Social Security benefit. This wife, if widowed, will receive the full Federal Civil Service survivor benefit her husband provided in addition to her own Social Security benefit.

Q. I called a local Social Security office yesterday to make an appointment for my wife and me to file for benefits. We have both reached full retirement age. The agent asked me when I wanted to start benefits. I didn’t know we had a choice. What answer should I give when we go to file?

A. You have the right to specify the exact month you want your Social Security benefits to begin. Benefits begun before full retirement age are reduced for each month of early retirement. Benefits begun after full retirement age are increased for each month that a benefit is deferred. This has always been a retiree’s option.

Q. I was always the primary earner. I am also 7 years older than my husband. I started taking Social Security at 66. He will turn 62 this year. His full Social Security benefit will be less than 1/2 of mine. If he files for his reduced benefits at 62, can he switch to half my benefits at full retirement age with no decrease in them? Or does his early reduction for his benefit transfer to mine for him?

A. When your husband files for Social Security, his application will cover both his own benefit and his spouse benefit. Each will be reduced for months of early retirement. In effect, he will receive whichever of the two benefits is the greater amount.

Q. I am a teacher in Texas and am ready to retire. I have the option of my husband receiving my full benefit or half of my benefit if I should die. How would this affect his Social Security benefits when he is eligible? Would you advise this? He does not have this type of pension, and I don’t want our kids to be burdened when they need to take care of us.

A. A survivor public annuity never affects a surviving spouse’s right to his or her own Social Security retirement benefit. The Social Security Act’s anti-windfall provisions cannot affect your husband’s Social Security benefit because he has not personally earned a public annuity.