Presumptive taxation under section 44AE: income fixed per vehicle, no further business deductions allowed, except partner payments and chapter VIA deductions. Income under the presumptive scheme of section 44AE is computed at fixed monthly rates per goods carriage (or per ton for heavy goods vehicles) and such presumptive income is treated as final, precluding separate business expense deductions and separate depreciation claims. Partnership firms may still claim deductions for partner remuneration and interest computed as per the Act. Written down value for assets must be calculated as if depreciation had been claimed and allowed, and chapter VIA deductions remain available.