Dear Liz: I am trying to decide whether to take Social Security at my full retirement age (66 years and four months) or wait and take it at 70. I am 64 and have two children, 13 and 11. My older child could get the child benefit for 24 months while my younger one would receive it for 41 months. Currently I am scheduled to receive about $2,600 a month at full retirement age or $3,500 at 70. My family maximum is $4,668 per month. I am having a hard time finding out what each dependent would earn monthly. Also, when my older child turns 18, does my younger child’s payment increase?

Answer: Starting Social Security earlier than age 70 means giving up the delayed retirement credits that otherwise would boost your checks for the rest of your life, and potentially those of a surviving spouse. As mentioned in an earlier column, though, child benefits complicate the math that typically favors waiting to claim Social Security.

Once you start your own Social Security benefit, each eligible child could get an amount up to 50% of your benefit. Eligible children are those who are unmarried and younger than 18, or under 19 if they’re still in high school, or 18 or older with a disability that began before age 22.

There’s a maximum a family can receive based on one worker’s earning record, however. The family maximum is 150% to 180% of the worker’s benefit. If your family’s total benefit would exceed that maximum, the children’s checks would be reduced, but yours would stay the same.

If you were receiving $2,600 a month, and your family maximum is $4,668, your children would split the remaining $2,068 and get $1,034 apiece. Once your older child is no longer eligible, your younger child’s benefit would increase to equal 50% of what you receive ($1,300, plus any cost of living adjustments).

If you were to start your benefit now, before your full retirement age, these checks would be subject to the earnings test that reduces the benefit by $1 for every $2 earned over a certain limit, which is $18,240 in 2020. The earnings test doesn’t apply after full retirement age.

Free Social Security claiming calculators typically don’t include child benefits as a variable, so you’d be wise to invest $20 to $50 in a more sophisticated calculator, such as Maximize My Social Security or Social Security Solutions.