Export turnover deduction permits tax deductions for exporters receiving convertible foreign exchange, with an additional incentive for increased exports. Section 80HHC provides tax deductions for exporters whose sale proceeds are received in convertible foreign exchange: a base deduction based on export turnover and an additional deduction for the increase in export turnover over the immediately preceding previous year, with the additional deduction contingent on having exported in that preceding year; specified exclusions and definitions of 'convertible foreign exchange' and 'export turnover' are set out.