At full retirement age (66) I filed and suspended my benefits. I have a son school age and he received dependent benefits. I am now turning 70 in July and will receive my full benefits. My son is 18 but has one more year of high school. SS states he will continue with benefits until completion of high school June 2018. Two questions: Will my son continue to receive benefits although I will receive my benefits when I turn 70 in July? Question number two. Will I be eligible for the 6 month retroactive payment? SS office I visited said yes.
Yes, your son can continue to draw benefits after you start drawing your benefits. Unless he has a disability, his benefits will likely end with the earlier of a) the month he graduates from high school, or b) 2 months after he turns age 19 (https://www.ssa.gov/OP_Home/handbook/handbook.03/handbook-0342.html).
Regarding your second question, the basic answer is yes you could elect to receive 6 months of retroactive benefits. However, if you do so you will lose your delayed retirement credits for those months, resulting in a 4% lower monthly benefit rate than you would receive if you wait until age 70 to start drawing. Larry believes that in most cases it's better not take the retroactive payments (https://www.forbes.com/sites/kotlikoff/2015/05/27/dont-let-social-securi...).