Online bankruptcy records, made available Sunday, show Lewis, 33, has assets of about $14.5 million and owes about $10.5 million, The Baltimore Sun reported.
Bankruptcy records show Lewis owes liens to Bank of America of $947,876 and $260,000 and to Mercedes Benz of $113,000, among other companies.
The U.S. trustee for the case has requested the bankruptcy be changed to Chapter 7 liquidation or dismissed because Lewis hasn't provided certain financial information and has not yet appeared for an interview in the case.
A hearing is scheduled for June 5 to consider that request.
Lewis, who spent seven seasons with the Ravens and three with the Cleveland Browns, is one of more than 2,200 other former players who are suing the National Football League, alleging the NFL concealed the health risks posed by concussions.
"[Concussion awareness is] something that I'm very concerned about," Lewis told the Sun in December. "It's just about getting the proper counsel and everything. It's more about [raising] awareness of where this is going and what it can lead to."
Lewis finished his NFL career in 2010 with 2,542 carries, 10,607 rushing yards and 58 touchdowns.