SSDI is based on disability and then on how many credits you earned during the years you worked. This year it's about
$1100 for each credit and then up to 4 credits a year.
So depending on your age when you are filing for disability, they will calculate whether you had enough credits in the last years you worked.
SSI is based on disability but it's a "needs based" system. This has nothing to do with previous work and only on whether you qualify financially now based on your current finances.
The federal amount given if approved for SSI is a max of $698 a month. However, there are many states that also supplement this if awarded disability. I, unfortunately, do not live in one that does this:(
SSDI amounts are only figured out at the end when approved based on an average of your income over the years you worked.
The website below is the .gov website that details all the info about SSDI...
Post Edited (Snowbunny21) : 9/25/2012 10:14:20 AM (GMT-6)