It refers to the gap between the real wage that the employee is getting and the wage that was discussed. There can be a rise as well as a downfall in the wage gap, depending upon several factors like bonus payments, less output and overtime. Wage drift is a common situation in several companies as while working, various employees get bonuses due to appreciated work, incentives or less output generated by employees or uninformed leaves.
There are several situations in which Wage drift can happen such as an increase in wages due to overtime working or a decrease in the wages when the output is decreased and there is no change in the wages or the worker is underused.