We change how we pay our employees with an 80base/20 performance pay scale. I had one employee go to a new position so for the first quarter we paid him 100% with no performance pay. I forgot to adjust his base wage down to the 80% at the beginning o

We change how we pay our employees with an 80base/20 performance pay scale. I had one employee go to a new position so for the first quarter we paid him 100% with no performance pay. I forgot to adjust his base wage down to the 80% at the beginning of the second quarter, so he was getting 100% plus his performance pay. I just noticed it now and the problem went on for eleven pay periods. What are my options?