Their regular wage was not wrong however their prevailing wages were calculated with the fringe benefit for overtime which has happened for 2 yrs. can we changed that?
For example employee johns regular wage is $15 hr, his prevailing wage is $16. + $2.33 fringe, however if he works overtime on a certified payroll job overtime is calculated by 1.5*$16=24+$2.33 fringe.
What would give you the basis to sue? How were you damaged or what economic damages did you suffer as a result of the overpayment? I don't think that you have "standing" to bring a lawsuit. If anyone is to be contacted it is the CO Department of Labor.
The information provided in this answer does not create an attorney-client relationship and is not considered to be legal advice.
With notice, you can certainly correct the pay moving forward.
As for seeking to recoup pay from the past two years, that probably isn't a good idea. Even if you don't care about the morale of your workforce, which would definitely be destroyed by such a move, there may be arguments of waiver or detrimental reliance that would prohibit recalculating wages that have already been paid.
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