(1) Where any person who has paid tax charged under an assessment to -
(a) income tax made for any year of assessment, or
(b) corporation tax made for any accounting period,
alleges that the assessment was excessive by reason of some error or mistake in the return or statement made by that person for the purposes of the assessment, that person may, at any time not later than 6 years after the end of the year of assessment or the accounting period, as the case may be, within which the assessment was made, make an application in writing to the Revenue Commissioners for relief.
(2) On receiving any such application, the Revenue Commissioners shall inquire into the matter and shall, subject to this section, give by means of repayment such relief in respect of the error or mistake as is just and reasonable; but no relief shall be given under this section in respect of an error or mistake as to the basis on which the liability of the applicant ought to have been computed where the retur