In case it appears that the amount paid with respect to any taxable transfer is more than the amount due under this Act, then the State Treasurer shall refund the excess to the person entitled to the refund, provided that no amount shall be refunded unless application for the refund is filed with the State Treasurer no later than one year after the last date allowable under the Internal Revenue Code for filing a claim for refund of any part of the related federal transfer tax or, if later, within one year after the date of final determination of the related federal transfer tax.