His name is on it, it’s his income to report

I see them often, one parent dies and their minor child gets SS benefits, if the son doesnt have any other income, theres no return to file for him.

Question seems to come up every year.  Here's my answer from last year, along with @IRonMaN 's flip remark.  

https://accountants.intuit.com/community/proconnect-tax-discussions/discussion/social-security-benef...

What I'm still not sure about is whether the "income in respect of decedent" is the amount that would have been taxable to the parent, based on the parent's income; or the amount that is taxable to the son based on the son's income.  For example, if the parent had no other income (which could happen with disability benefits), then none of the retroactive payment could be taxable. On the other hand, if the son has $100,000 of income, then 85% of the Social Security could be taxable.  

Does the 1099-SSA also have the name and SSN of the parent somewhere on it?  That might be helpful. Whatever method you choose, I would report it as "other income," not on the line for Social Security benefits, and attach an explanation.  But I would still be prepared for a CP-2000, if using the son's income it comes out as taxable.  

He's not a minor child, and his SS income is 85% taxable, whereas his mom's was not taxable. I just wondered why it didn't go to the deceased or to her estate. I truly have never seen this from hundreds of my deceased clients and their adult children.  It has "his name O/A/O his mom's name deceased"... what is O/A/O?

Google is your friend:

The deceased mom was not married. The SSA-1099 did say "OAO=On Account Of Deceased Mom's name" but the SSN was the adult's son, who did receive the final SSA monthly payment.