AUGUSTA – Department of Health and Human Services took several months to address a computer error that ultimately caused more than $10 million worth of overpayments to MaineCare recipients from 2010 to early 2012, according to a state report.

The commissioner of the DHHS didn’t know about the problem until late December 2011 and didn’t know the scale of the problem until March of this year, when the department alerted the governor and Legislature, the report says.

The Office of Program Evaluation and Government Accountability released its report Thursday on the computer problem that sparked a partisan battle among lawmakers in March.

The office focused on the communication within the DHHS and the timing of Commissioner Mary Mayhew’s decision to alert the governor and Legislature.

Democratic lawmakers demanded the review, saying they should have been told about the problem during budget deliberations last winter.

Weakness in the computer system for MaineCare — the state’s Medicaid program — caused more than $10.6 million in payments to as many as 19,000 ineligible patients from September 2010 to March 2012.

The report says DHHS staff members and a state contractor knew about the problem as early as March 2011 but didn’t know the severity of the computer glitch. It was placed on a long list of computer problems that had to be addressed, but was not identified as a top priority.

It wasn’t until outside agencies started asking questions about MaineCare payments that the problem reached the commissioner’s office, in late December.

The report by OPEGA was presented Thursday to the Legislature’s Government Oversight Committee, which is expected to hold a public hearing on the report at a future meeting.