Yes, you can claim an adult that's disabled on your tax return. Since he's your son, he could be treated as a qualifying child and you may also be eligble for Earned Income Credit for him. The following tests have to be met to claim your adult son as a qualifying child:
1. Relationship: met (he's your son)
2. Age: met (since he's disabled, there's no age limit)
3. Residence: if he's lived with you more than 6 months, this is met
4. Support: if he didn't pay more than half of his own support, this is met
If all of the above tests are met, you can claim your son as a dependent and for Earned Income Credit. Additionally, if you paid someone to care for him while you were working, you may qualify for the Child and Dependent Care Credit.
