Tax on unexplained income: special high-rate tax applies plus separate tax on remaining income after exclusion. Income classified as unexplained-either reflected in the return or determined by the Assessing Officer-is taxed by aggregating a special tax on the unexplained amount at the prescribed high rate and the normal tax payable on the remaining income after reducing total income by that unexplained amount; no deduction, allowance, expenditure or set off of loss is permitted against the unexplained income.