Since he is not a dependent, he will get his full $12K standard deduction, so it's not critical where it gets entered.
The IRS considers anything
in box 7
of 1099-MISC to be self employment income. TurboTax (TT) aggressively steers
you in that direction, even when the amount is in box 3.
That said, the key to
getting TT to treat it as other income is to follow these steps:
Enter the 1099-Misc
On the next screen Describe
what the payment was for
On the next screen
select "none of these apply"
On the next screen select
"No it didn't involve work like my main job"
On the next screen select
"I got it in 2018" ONLY (Lying to TT to get it to do what you need does not constitute lying to the IRS)
On the next screen
select No, it didn't involve intent to earn money
TT will put the amount
on line 21 of form 1040 (Schedule 1) as other income
