The ITS replaced a mainframe application with Java-based software that runs on IBM's WebSphere middleware platform and DB2 database.

CGI and DOR engineers in recent weeks have been analyzing data and testing to make sure that all defects are addressed, Engan said.

The DOR has calculated that it still owes 33 counties $1.8 million, while it has overpaid $2.8 million to 25 counties and the two sports districts, according to a report by State Auditor Janice Mueller.

In an interview, Mueller urged caution before collecting the remaining overpayments until the testing is complete and the ITS system is proved reliable.

Mueller also said that the DOR has agreed to provide monthly reports, starting in February, to the state legislature on the progress of the ITS repair effort.