SSDI is a merit based program, and what that means is the more money you pay into the system, the more benefits you can receive. And because it's a merit based program, the government is not concerned about what kind of income you have, or what kind of assets you have. You could be Bill Gates, and have all this money, but if you become disabled, you will receive benefits.
SSI is a charity based program based on financial need, so the government is very concerned about how much income you have, how many assets you have. So as an individual, you can't have more than $2,000 worth of assets, as a family, no more than $3,000.
As far as the income requirements go, they're very complex, but it's a lot like applying for food stamps, or Medicaid. The more money you get, the less your benefits. If your income is too high, then you'll be excluded financially from being eligible for this program.
If you are someone that's thinking of filing for SSD, and you're considering either one of these two programs, give us a call, fill out the form online. We know what we're doing. We've helped thousands of people. We'd love to help.