The government has named employers that did not pay some staff the minimum wage.
The official list includes Northern Ireland businesses, racing trainers Alan King and Lucinda Russell, and retailer B&Q.
Those named are expected to repay the money owed to employees.
Separately, recent reports suggest that wages are trailing inflation.
That is a worrying economic indicator.
Prices are climbing more quickly than wages, leaving workers with lower real incomes.
The government list and the pay data demonstrate financial strain for workers.
Officials said fresh action would follow for employers that underpaid workers.