Last month, the state's Office of the Legislative Auditor released a financial audit that looked into whether state agencies paying the most in overtime and business expenses have adequate controls over these payments.

The bottom line? It's a mixed bag.

The study found that the departments of Corrections, Human Services, Natural Resources, Public Safety and Veterans Affairs all had "adequate" internal controls to ensure that they accurately paid employees for authorized overtime. They complied with payroll and other legal requirements related to overtime, as well.

But the auditor concluded that the Minnesota Department of Transportation "needs to strengthen some controls."

This oversight is important because it involves some serious coin. Between July 1, 2013, and June 30, 2016, the state's total overtime expenses were about $270 million.

During this period, the Minnesota State Colleges and Universities system paid the most in overtime, about $65 million — followed by Human Services, at nearly $59 million and then MnDOT, at $38 million. The audit report does not indicate the overtime per employee at these agencies, making comparisons difficult.

An unnamed employee at DHS was the top overtime earner, making $294,493 in overtime over the past three fiscal years.

Overtime typically is related to road construction projects, bad weather emergencies and public safety hazards, and to human services and correctional sites that operate 24 hours a day, the study states.

Employees usually file for overtime if they work shifts on their scheduled days off on top of their regular shifts. Employees working on special projects, such as MNsure, sometimes find themselves in overtime situations, too.

Overtime and employee expense reimbursement have a higher risk of calculation errors and noncompliance with federal regulations because of the complexity of the laws and the differences among union contracts covering state employees. About 30,000 of the state's 52,000 employees are eligible for overtime under federal law.

The report notes that the state was named as a defendant in a class-action lawsuit filed in 2015 that alleges the state failed to properly calculate overtime pay in certain situations, a violation of federal law. The suit is pending.

The report found in some cases, MnDOT supervisors without direct knowledge of employees' work approved overtime. MnDOT uses a different system than other state agencies for tracking overtime, and "may be paying employees based on inaccurate or unauthorized time reported," the report said.

The auditors recommended that MnDOT improve its overtime processes.

In a letter to legislative auditor James Nobles, MnDOT Commissioner Charles Zelle said the department "believes strongly in financial integrity" and will improve its internal control processes by next April.

The conservative Freedom Foundation of Minnesota called the report shocking and questioned why it will take MnDOT until April to fix its system. "It will take MnDOT seven months to make sure that they're not wasting tax dollars by paying overtime that may or may not be warranted," said Annette Meeks, the foundation's CEO.

"During nearly every legislative session for the past decade, state bureaucrats appear before legislative committees and submit their requests for additional tax dollars," she said. "No state agency has been as aggressive as MnDOT in the pursuit of raising taxes to increase their budget."