Dear Liz: Having read your advice on Social Security numerous times, I’m having a heck of a time encouraging a friend who reached full retirement age last year to start collecting her benefits. She said her Social Security isn’t enough to live on and she needs to work two more years before collecting. She said if she waits to apply that it would increase her Social Security by $400 a month. I’ve informed her that she can both collect and continue to work without penalty because she has reached full retirement age. She also would still get an annual increase based on her earnings, in addition to the annual cost-of-living increase. She won’t let me know how much her Social Security would be now, and I haven’t asked, but I’ve told her this is extra money she could invest.

Answer: Are you sure you were reading this column?

Copious research shows that most people are better off waiting as long as possible to file for Social Security. Given life expectancies at 65, most who make it that far will live beyond the break-even age where the larger checks they’ll get will more than offset the smaller ones they pass up.

Waiting is particularly important for the higher earner in a couple, since that determines what the survivor gets to live on. Waiting is also important for single people, since they don’t have a partner’s income to help. Single women have an especially high risk of finishing their days in poverty, which means maximizing their Social Security is usually the right call.

Besides, there’s no risk-free investment that would guarantee her an 8% annual return. That’s what she’s getting by waiting to start her Social Security benefit (at least until age 70, when the benefit maxes out). She might be able to generate similar returns with stock market investments, but she also could lose her shirt.

Something else to consider: Benefits are based on our 35 highest-earning years. If she’s making more now than she did in one of those previous years, she could be boosting her benefit even more by continuing to work. People who took time off to raise families or who had a history of low wages or part-time work often see a bigger benefit by continuing to work as well as waiting to apply.