A series of decisions by the state Department of Taxation on computer services contracts is coming under scrutiny.

State Auditor Marion Higa on Wednesday released an audit criticizing the agency for a decade-long series of decisions regarding technology services from CGI Technologies and Solutions Inc. and predecessor American Management Systems Inc.

According to the audit, the agency suffered from disputes between its workers and the vendor.

The report also found that a contract modification last year increased the vendor’s compensation by millions of dollars before it completed services required by a 2008 agreement.

It says department technology staff, which is stretched thin, may be unable to sustain the computer system beyond June.