Madigan sent letters to Indeed, Beyond.com, Ladders, Monster Worldwide and Vault as well as CareerBuilder requesting information about functions that appear to keep older people from building accurate resumes or profiles.
The drop-down menus on all of these platforms only offer 1980 as the earliest possible start date for education or previous employment. Other job portals use dates ranging from 1950 to 1970 as cut-offs.
"Today's workforce includes many people working in their 70's and 80's," Madigan said in a press release. "Barring older people from commonly used job-search sites because of their age is discriminatory and negatively impacts our economy."
Under the attorney general's Civil Rights Bureau, which enforces state and federal civil rights laws, is examining the practices. Excluding older workers could violate the Illinois Human Rights Act and the federal Age Discrimination in Employment Act.
In an email, CareerBuilder spokeswoman Jennifer Sullivan Grasz said the company "is committed to helping workers of all ages find job opportunities, and is fixing this unfortunate oversight."
The other job portals involved are yet to address the issue publicly.