Filing a claim for SSDI benefits is the same as filing an insurance claim where the Social Security Administration is the insurance carrier. Just like you have to pay premiums to maintain your automobile insurance, you have to pay into Social Security for at least 5 out of the last 10 years to be insured by SSA and to be eligible to receive benefits from them.
Social Security will look at your last 10 years of work and federal tax returns to determine your DLI. For each year that you have worked and paid taxes, you earn 4 credits. To be eligible for SSDI, you must have at least 20 work credits on your record.
Everyone's DLI will be different depending on their work history, so you will need to call SSA to find out your specific DLI. But generally, your DLI is 5 years after your last day of work. Just like auto insurance provides additional coverage past the length of your policy, SSA provides coverage for about 5 years past your last day of work.
Your DLI is important because SSA will only pay claimants that were insured at the time of their disability. If a driver is involved in an accident, their auto insurance policy will only cover the claim so long as the accident occurred while the motorist was still insured. Similarly, SSA will only pay you benefits if your disability occurred while you were still insured, meaning before your DLI date.