Denver recently made a complex conversion to a new payroll system, and while it was largely successful, a lack of controls resulted in some errors, according to an audit.

In one instance, an employee’s annual salary was set at the biweekly rate, and an incorrect payment was made, Auditor Timothy O’Brien’s office said in a press statement. The error was remedied after the employee reported it.

Other mistakes found during the system change included incorrect vacation accruals, a terminated employee receiving paychecks for months after leaving and over and underpayments.

The number of errors is not out of the ordinary for such a large-scale change, O’Brien’s office said, but they cropped up due to a lack of controls.

In the audit report, O’Brien’s office recommends the city’s Controller’s Office, the department responsible for accounting and payroll, develop procedures and training for finding errors and solving them.

Some city departments have had recurring issues with supervisor timesheet approvals, the auditor’s office said. There are no procedures for missing timesheet approvals, with 11 percent of employee timesheets going unapproved while checks were still being issued by payroll.

“This creates a risk of someone being paid for no work,” O’Brien’s office said. “There was no direct evidence of payroll fraud identified in this audit report.”

Denver also does not appear to have a reliable timecard approval report for all public safety employees, since January 2017, according to O’Brien’s office.

“This could mean overtime, vacation time or other exceptions to regular hours worked could go unreported and unreviewed,” the statement said.

The Controller’s Office has agreed to implement the audit report’s 19 recommendations before or by December 2017.