SSDI is not reportable income and this payment is not enough to make you require a federal tax return, You would only want to file if tax was withheld from the payment.
There are some few states that require you to file a state return if you have any kind of potentially taxable income. If you tell me what state you live in, I'll look that up for you, and if you'll tell me what the lawsuit was for, meaning medical damages or bills, or what. You can also simply call your state and explain the nature and amount of the income and ask them.
