By Brendan Pierson

March 4 (Reuters) - A court-appointed special master has found that U.S. authorities do not have evidence to support their billion-dollar fraud case accusing UnitedHealth Group UNH.N of keeping overpayments from the government for patients on its Medicare insurance plans.

The recommendation by Special Master Suzanne Segal on Monday is not a final ruling, but if it is adopted by U.S. District Judge Fernando Olguin, it would end the U.S. Department of Justice's claims against the health insurer.

"After more than a decade of DOJ’s wasteful and expensive challenge to our Medicare Advantage business, the Special Master concluded there was no evidence to support the DOJ’s claims we were overpaid or that we did anything wrong," UnitedHealth said in a statement.

The Justice Department did not immediately respond to a request for comment.

The government claimed in its 2016 lawsuit that UnitedHealth submitted false diagnoses for patients on its government-funded, privately administered Medicare Advantage plans in order to get higher payments. Medicare reimbursements to insurers that administer Medicare Advantage plans are tied to patients' diagnosis codes, with sicker patients getting higher reimbursements.

However, Segal wrote on Monday that the government's case relied on discrepancies between diagnoses submitted by doctors making claims and later determinations by UnitedHealth's coders. She said that did not show that any of the original claims were false, concluding that there "simply was no fraud."

(Reporting by Brendan PiersonEditing by Bill Berkrot)

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