The other part of that question would be how do you figure out the 50% support piece.
That doesn't figure in to the equation per-se. If your son is not gainfully employed, there is no possible way he can provide more than 50% of his own support.
Additionally, if you take a look at IRS publication 17 at https://www.irs.gov/pub/irs-pdf/p17.pdf and see the chart for "Test to be a qualifying child" on page 27, the requirement is that the child provided more than half their own support. There is no requirement for the parent to provide any support - not a single penny.
Social Security does not count for the child providing their own support.
As for the SS check, would he be able to support himself on it, if he was not living with you? Most likely, no.
But it's not the amount of money he receives that matters. It's the amount of support the child pays for that matters. So he could be receiving $10,000 a month. But if he's only providing and paying $1000 a month and that comes to 30% of his own support, he qualifies as your dependent.
Be aware of what is included in support also. It's not just rent.
-Food
- Clothing
- Housing
- Utilities
- Transportation
- Entertainment
and that's not anywhere near all-inclusive either.
