Wal-Mart Stores has vowed to pay more than US$33m in back wages to thousands of employees because it paid too little in overtime, according to the US Labor Department.

Wal-Mart brought the matter to the attention of the Department of Labor after an internal audit raised concerns regarding overtime computations.

The concerns included how Wal-Mart treated incentives and other premium payments in the calculation of employees' overtime pay, and how it addressed payment of overtime to certain non-exempt salaried interns, manager trainees, and programmer trainees.

The department filed the complaint today (26 January) in the US District Court for the Western District of Arkansas, Ft. Smith Division, against Wal-Mart Stores alleging violations of the FLSA overtime provisions. It said the court approved a consent judgment ordering the company to pay the wages and enjoining it from further violations this morning.

Wal-Mart has agreed to pay all back wages the Labor Department has determined are owed for violations identified in the consent judgment. The company has also set up a website and a toll-free telephone number to answer questions regarding the back wages.

The department said the issues arose under the Fair Labor Standards Act (FLSA) concerning how the company computed overtime pay. The agreement covers 86,680 employees who worked for the company from 1 February 2002 to 19 January 2007, it said.

"This settlement provides $33m in back wages, plus interest, to Wal-Mart workers, and the company has taken corrective action to prevent this from happening again," said assistant secretary of Labor for Employment Standards, Victoria Lipnic.