More than one third of the businesses audited by the District of Columbia Minimum Wage and Safety Board in the past year were caught shortchanging their employees.

The board said yesterday it found 2,278 workers lost an average of more than $100 each because their employers failed to pay them the minimum wage or give overtime pay.

Audits by the board's staff of 1,154 businesses found 402 had underpaid their workers by a total of $285,000. After the audits, $263,000 in back pay was collected; most of the rest could not be claimed because the employers had gone out of business.

The board said 61 per cent of the underpayments - about $174,000 - resulted from failure to give overtime pay. The remaining $111,000 was owed to employees who did not receive the city's minimum wage.

The District's minimum wage varies from $2.40 an hour to $2.90 an hour, depending on the job. Three member boards - one from labor, one from management, one independent - set the rates for each occupation.

In an announcement yesterday, the board said restaurants and apartment house management firms were the worst wage law breakers. They underpaid their workers by $135,000. Retail stores were next on the list, underpaying workers by $59,000.

The wage board regulates pay and working conditions for 300,000 workers in 15,000 businesses.