If any individual or organization shall make application for refund or credit of any amount paid as contribution, interest or penalties, under this act, and the department shall determine that such amount, or any portion thereof, was erroneously collected, the department may at its discretion either allow a credit therefor, without interest, in connection with subsequent contribution payments or shall refund from the Unemployment Compensation Fund, without interest, the amount erroneously paid: Provided, That an amount equal to any refund or credit of interest and penalties allowed, as provided herein, shall be transferred from the Special Administration Fund to the Unemployment Compensation Fund, irrespective of whether such interest or penalties were paid into the Unemployment Compensation Fund or into the Special Administration Fund: And provided further, That any refund or credit allowable under the provisions of this section, of contributions paid with respect to remuneration (1) exempt under the provisions of section 4, subsection (x) of this act,¹ or (2) paid with respect to services exempt under the provisions of section 4, subsection (l)(4) of this act, shall be reduced by the amount of unrefunded compensation paid to any claimant by reason of the inclusion of such remuneration in the base-year wage credits of such claimant. No refund or credit shall be allowed with respect to a payment as contributions, interest or penalties, unless an application therefor shall be made on or before, whichever of the following dates shall be the later: (a) one year from the date on which such payment was made, or (b) four years from the reporting due date of the reporting period with respect to which such payment was made. For a like cause and within the same period, a refund may be so made or a credit allowed on the initiative of the department.

An amount paid as contribution, interest or penalties shall not be deemed to have been erroneously collected within the meaning of this section if such amount was collected under and pursuant to a notice of contribution rate or a notice of assessment which, because of the applicant's failure to file a timely appeal therefrom, shall have become binding and final against the applicant under the provisions of this act.

In any proceeding instituted to obtain a refund alleged to be due and owing under the provisions of this section, the Adjustment Factor as determined by the department under the provisions of section three hundred one point one (301.1) of this act² for the calendar year one thousand nine hundred sixty, and any calendar year thereafter, shall not be subject to review or redetermination.