PP poster here: It should also be mentioned that a lot of people who are disabled don't "look" disabled. There are people who have very severe psychiatric impairments who have no physical limitations. So you may see people on disability who can mow their lawn, pick up gallons of milk, lay brick, whatever. But they may not be functioning well on the inside. If you think you have proof that your parents are truly not disabled under Social Security's definition of "disabled", then you should report them. Otherwise, be open to the fact that there might be more going on that meets the eye.

there are lots of people who genuinely need it and lots of people who abuse the system. I'm a family doctor who has worked in rural areas and in some depressed areas 50% of all my adult patients were on SSDI. It's a way of life for many.

Here is Social Security's Definition of what "disabled" means:
The definition of disability under Social Security is different than other programs. Social Security pays only for total disability. No benefits are payable for partial disability or for short-term disability.
"Disability" under Social Security is based on your inability to work. We consider you disabled under Social Security rules if:
•You cannot do work that you did before;
•We decide that you cannot adjust to other work because of your medical condition(s); and
•Your disability has lasted or is expected to last for at least one year or to result in death.
This is a strict definition of disability. Social Security program rules assume that working families have access to other resources to provide support during periods of short-term disabilities, including workers' compensation, insurance, savings and investments.

See: http://www.ssa.gov/dibplan/dqualify4.htm

If you suspect your parents are not disabled and they are collecting benefits while they should be able to work, this could be considered fraud. These are pretty serious accusations you have brought up on here about your parents. People who are not disabled under Social Security's definition of disabled, but who are collecting Social Security DISABILITY benefits, may be (are probably) committing fraud. See more here:
http://oig.ssa.gov/report-fraud-waste-or-abuse
http://ssa-custhelp.ssa.gov/app/answers/detail/a_id/48/~/reporting-social-security-fraud

You may want to have a talk with your parents or call the SSA line to discuss this.