An attorney can help you get SSDI back pay in Chicago by properly documenting the onset date of your disability, presenting a solid case for back pay, ensuring an accurate calculation process, and representing you in case of disputes. When your Social Security Disability Insurance (SSDI) claim is approved, you may be entitled to monthly payments as well as back payments for the period before your approval date. An SSDI attorney will be crucial in proving you qualify for SSDI benefits and back pay.