Unfortunately, what has been happening in the recent past is that many individuals have attempted to use the SSDI system (Social Security Disability Income) as a substitute for their inability to find work because of a lack of job skills.
If someone is unable to read or write, that puts a severe limitation on the jobs that he is qualified for.
There are many job training (retraining) programs that he would qualify for & perhaps that is a route to consider.
As far as qualifying for the SSDI program, the only way to determine if he qualifies is to make an application.
He can make an appointment with his local Social Security office and meet with a representative who will be able to assist with the application process, if after interviewing him he qualifies for coverage.
The next step would then be to work with the representative to complete the application. They will actually complete the application for him as part of the interview process. He can bring an advocate with him to the interview (perhaps you would be willing to go with him) to assist him and to make sure that he understands the questions and to further assist as he is unable to read or write on his own.
You should note that in the SSDI system, there is no partial disability; you are either 100% disabled and unable to work or you are not disabled. If, as you say, he is willing and able to work, perhaps even as a laborer, and not physically or mentally unable to work, then he will not qualify for SSDI.
However, it is definitely worth the time & energy to at least visit his local Social Security office to confirm his tentative status, so he at least can consider all of his options.
You can call the Social Security Administration to set up an appointment at 1-***-***-**** or use the following link to see if your local office has a dedicated Appointment Scheduling number:
Finally, I would also suggest that he contact your state's Department of Employment Security to see what job training programs he may qualify for; I know that there are federally funded job training-retraining programs for
"ex-cons" as well as referral services for employers that have hiring practices that include affirmative action programs to hire previously incarcerated individuals who have served their time and are making a good faith effort to return to productive members of society.
That should give you the information to help your friend get started in trying to find a workable solution to the issues he is facing. It seems to me that what he needs most at this point is a good friend willing to assist him in working through the administrative "red tape" that he must deal with to get back on track. If you are willing to fill that role, he'll be off to a good start.