If you have a long-term disability you can (and should) apply for SSDI benefits. But be prepared for a lengthy and difficult process. To qualify for SSDI, you have to be unable to do any occupation (not just the occupation you had before your disability that you may have specially trained or were educated for) and have been totally disabled for at least 5 months. Also, be aware that nearly 65% of initial SSDI claims applications are denied. And, if you successfully appeal the denial, it could take up to 2 years to start receiving benefits. If approved, the average monthly benefit paid by SSDI is around $1,000 a month. Consider whether you could wait that long and live on that amount if you had a long-term injury or illness that kept you out of work.