Restriction on unabsorbed allowances limits current deduction and mandates carryforward or addition to subsequent years for domestic companies. Restriction on unabsorbed allowances for certain domestic companies limits the deductible portion of unabsorbed depreciation and investment allowance for the assessment year commencing in 1992, requiring the balance of unabsorbed depreciation to be added to and treated as subsequent years' depreciation allowance and unabsorbed investment allowance to be carried forward and, if an eight-year expiry would prevent adjustment, extending that period until the balance is absorbed; the restriction is subject to a statutory threshold and preserves application of non-conflicting depreciation rules while exempting certain interest and penalty provisions where shortfall is timely paid before filing the return.