Deductions & credits

@Block33  

That doesn’t explain whether it is SSI or SSDI.

 

If it is SSI, then I suspect the regulations require  that he disclose that he is being supported by someone else, regardless of whether you claim him on your tax return.  You may wish to have a consultation with some kind of social worker or benefits expert in your area. Often times, the rules for SSI vary from state to state.