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Federal authorities have officially launched a complaint against insurance giant UnitedHealth Group in a lawsuit claiming the company “knowingly disregarded” beneficiary information in order to receive higher Medicare Advantage payments.

The Department of Justice announced it was joining the lawsuit in March. Days later, federal authorities filed to combine the lawsuit, which was filed by a whistleblower in 2009, with a similar case filed in 2011. That motion was terminated in late April, according to court records.

The DOJ’s complaint, filed Monday, argues that UnitedHealth disregarded information about Medicare Advantage beneficiaries’ conditions, which boosted the federal payments the insurer received. One particular instance described in the filing claims that UnitedHealth funded chart reviews conducted by provider HealthCare Partners in order to increase risk adjustment payments for Medicare beneficiaries.

“However, UHG allegedly ignored information from these chart reviews about invalid diagnoses and thus avoided repaying Medicare monies to which it was not entitled,” the DOJ said in a statement.

A spokesman for UnitedHealth said in a statement to media, “We are confident our company and its leaders complied with Medicare Advantage program rules and were transparent with [federal officials] about how we interpreted the government’s murky policies.”

UnitedHealth plans to “contest [the DOJ claims] vigorously,” the spokesman said.