Presumptive taxation for foreign turnkey power project contractors deems profits at a fixed rate with audit-based lower income option. A special presumptive regime applies to foreign companies undertaking civil construction, erection, testing or commissioning work for approved turnkey power projects. Profits are deemed at 10% of the relevant amounts paid or payable, subject to a lower-income claim only where prescribed books are maintained and audit requirements are met. The regime overrides contrary computation provisions, disallows other deductions against the computed income, and treats assets as if depreciation had been claimed and allowed.