Presumptive taxation for aircraft operators: freight receipts of non-resident operators taxed under special provision as business income. A special presumptive computation treats freight receipts received or deemed received in the country by non-resident aircraft operators as business income taxed at a prescribed presumptive rate, precluding declaration of income below that rate. Ordinary business provisions do not apply to reduce that presumptive income; current-year and brought-forward depreciation from other businesses cannot be set off against it, while current-year and carried-forward losses from other businesses may be set off. Chapter VI-A deductions remain available.