(a)no loss incurred in any year prior to the tax year shall be carried forward and set off against the income of the tax year unless on the last day of the tax year, the shares of the company carrying not less than 51% of the voting power were beneficially held by the person who beneficially held shares of the company carrying not less than 51% of the voting power on the last day of the year or years in which the loss was incurred; and