Income from Other Sources taxation of business trust distributions follows the specified sum formula after exclusions and prior-tax adjustments. Income received by a unit holder from a business trust is taxed as Income from Other Sources as a specified sum computed by the formula A-B-C, with nil deemed where B and C exceed A. A is the aggregate distribution in respect of the unit, excluding specified interest, dividends, and amounts already taxed at trust level; B is the original issue price of the unit; and C is the amount already taxed under the clause in earlier years.