Your date last insured (DLI) can be an important date for your Social Security disability claim. Social Security disability is an insurance program, and a portion of the FICA payroll taxes withheld from every paycheck pays the disability premium. However, if you stop working, you stop paying the premium. Eventually, your disability insurance will lapse. The date your insured status ends is called the "date last insured."
The DLI can be a trap for a disability claimant. To prevail with a Social Security disability claim, you must show that your were disabled prior to your date last insured. It does not matter how badly disabled you are today. If you cannot demonstate that you were disabled prior to your DLI, you will be denied disability benefits. You still may be elegible for SSI benefits, but you must qualify financially for SSI benefits.
If you are applying for disability benefits and have a DLI in the past, you really should consult a Social Security disability lawyer.