Recovery of unrelieved surplus ACT wrongly set off
19. If an officer of the Board discovers that any set off of unrelieved surplus ACT of a company by virtue of regulation 14 ought not to have been made, or has become excessive, the officer may make any such assessments as may in his judgment be required for recovering any tax that ought to have been paid and generally for securing that the resulting liability to tax (including interest on unpaid tax) of the company is what it would have been if only such set off had been made as ought to have been made.