Unexplained expenditure treated as income: attracts a special high tax charge, surcharge and restricted deductions. Expenditure lacking a satisfactory explanation may be deemed income and is not deductible under any head; when such amounts are included in total income a special tax regime applies requiring an aggregate tax computation comprising a high tax charge on the included amounts plus tax on the balance, with no deduction or set off allowed against those included amounts, a surcharge on the tax computed, and an additional percentage penalty subject to a disclosure exception.