A False Claims Act lawsuit accuses several health insurers—including UnitedHealth Group, Health Net, and Humana—of engaging in a scheme since 2006 to submit inflated claims for payment to the Centers for Medicare & Medicaid Services (CMS) by reporting false “risk adjustment” information in order to improperly increase the amounts CMS pays them or their clients. The lawsuit alleges the companies collected payments from claims that they treated patients for conditions they did not have or for diagnoses that didn’t meet the requirements for risk adjustment. The lawsuit alleges the companies have defrauded the United States of hundreds of millions, possibly billions, of dollars.