The attorney general, Xavier Becerra, said he would file the lawsuit this week in state Superior Court. The complaint will focus on how Navient guided borrowers through their repayment options. The company failed to steer borrowers toward the best options available to them, raising the repayment costs for some, according to Mr. Becerra's office, which said it believed that Navient broke state laws prohibiting unfair competition and false advertising. "Navient's loan servicing abuses have compounded the misery of parents and students who sacrificed to pay for college," Mr. Becerra said. Navient called the allegations "unfounded" and said it would fight the lawsuit. California's suit "is another attempt to blame a single servicer for the failures of the higher education system and the federal student loan program to deliver desired outcomes," John F. Remondi, Navient's chief executive, said in a statement.