ST. PAUL, Minn. — Minnesota's legislative auditor is preparing to release a special review of big overpayments made by the state Department of Human Services to two tribes for opioid treatment programs.

The department has overpaid the White Earth and Leech Lake bands of Ojibwe by an estimated $29 million since 2014.

The Office of the Legislative Auditor will present its findings to the Legislative Audit Commission at 2 p.m. Tuesday.

The bands say they were following the department's billing instructions when they charged Medicaid for office visits for patients to receive medication to help wean them off opioids, even though the patients took the medication at home. Medicaid pays more for treatment administered a clinic.

The department has said it's legally obligated to recover the overpayments from the tribal governments despite their objections.