If, not later than four years after the date on which any contributions or interest or employment security administrative contingency assessments became due, an employer who has paid the contributions or interest or employment security administrative contingency assessments shall make application for an adjustment in connection with subsequent contribution or employment security administrative contingency assessments payments or for a refund because the adjustment cannot be made and the commission shall determine that the contributions or interest or employment security administrative contingency assessments or any portion was erroneously collected, the commission shall make an adjustment, without interest, in connection with subsequent contribution or employment security administrative contingency assessments payments by him or, if the adjustment cannot be made, shall refund the amount from the fund. For like cause and within the same period an adjustment or refund may be made on the commission's own initiative.

A refund or adjustment must be made in any case where the commission finds that contributions or interest or employment security administrative contingency assessments were erroneously paid by an employing unit to this State upon wages earned by individuals in employment in another state. The refund or adjustment must be made upon satisfactory proof to the commission that the payment of the contributions or interest or employment security administrative contingency assessments has been made to the other state.