Make those who were overpaid pay the “overpayment” back!
I don’t necessarily agree with that. You are offered a promotion and that comes with a salary bump. It sounds like a policy was in place that you get either the minimum of the grade that you are moved to or a maximum 10% raise. That really is the employers job not yours to make sure the offer is not above their policy. In the private sector, there is no way that they could make you pay that back if they screwed up.
Instead of punishing the people who made the mistake, they are punishing the employee test got the promotion. The people that should be punished are managers in the HR/compensation groups.
“Errors in setting pay, especially those discovered years after they were made, can have a significant impact on employees because employees are required to reimburse the IRS for the amount of the overpayment,” said the IG.