LinkedIn Corp. paid almost $6 million in unpaid overtime pay and damages to 359 current and former employees in California, Illinois, Nebraska and New York after a U.S. Department of Labor investigation found that the San Francisco company violated the overtime and record-keeping provisions of the Fair Labor Standards Act.

When notified of the violations, LinkedIn agreed to pay all the overtime back wages due and take steps to prevent repeat violations, the labor department said in a press release.

The law requires that covered, non-exempt employees be paid for all hours worked, plus time and a half for hours worked beyond 40 per week. Sources within the department who agreed to speak anonymously said the investigation focused on LinkedIn employees in marketing, recruiting, talent and sales who — based on their duties — should have been eligible for overtime pay but were classified as exempt from overtime. Because they were exempt, LinkedIn did not track their hours. But based on interviews with several employees, the investigators found that on average, they worked about five hours per week of overtime.

Employers who violate the law are generally required to pay employees back wages and an equal amount in liquidated damages. LinkedIn paid about $3.3 million in back wages and $2.5 million in liquidated damages and agreed to provide compliance training and make sure non-exempt employees and their managers understand the law.

The labor department can reduce liquidated damages if a company has a good faith defense for not complying with the law, such as advice from a lawyer or accountant. The department would not say why it reduced liquidated damages in this situation. (An earlier version of this blog quoted an e-mail from a labor department spokesman who implied it was because LinkedIn engaged in a comprehensive, enhanced compliance agreement.)

Workers who were misclassified received anywhere from $270 to $34,127 based on their rate of pay and length of employment. The median payment was $11,824.

A LinkedIn spokesman explained in an e-mail, “This was a function of not having the right tools in place for a small subset of our sales force to track hours properly; prior to the DoL approaching us, we had already begun to remedy this. LinkedIn has made every effort possible to ensure each impacted employee has been made whole.”

For more information about the federal wage laws, employees can call the labor department’s wage and hour division’s toll-free helpline at 866-487-9243 or visit www.dol.gov/whd.