My son, who lives with me, is 21 and has autism spectrum disorder. He receives SSI every month. I already claim him on my taxes, but should it be as a disabled child?

[chuckd1991]

He is also still a student in the local school district, as part of their continuing education program for people with disabilities.  

[macuser_22]

"Disabled" only allows you to claim a Qualifying child beyond the normal cutoff age of over 18 (or over 23 if a full-time student).  There are no other benefits for marking disabled.  If already a full-time student then it would not change anything.  

Disabled for tax purposes means:

Permanent and total disability.

You have a permanent and total disability if you can't engage in any substantial gainful activity because of your physical or mental condition. A qualified physician must certify that the condition has lasted or can be expected to last continuously for 12 months or more, or that the condition can be expected to result in death.

Substantial gainful activity.

Substantial gainful activity is the performance of significant duties over a reasonable period of time while working for pay or profit, or in work generally done for pay or profit. Full-time work (or part-time work done at your employer's convenience) in a competitive work situation for at least the minimum wage conclusively shows that you are able to engage in substantial gainful activity.

IRS Pub 524
https://www.irs.gov/publications/p524#en_US_2017_publink100038680

[SweetieJean]

There may be some State tax benefit.