Computation of profits for oil and gas businesses: gross receipts minus allowable business expenditures determine taxable profits. Profits of a mineral oil or natural gas business equal gross income from that business less business expenditure wholly and exclusively incurred. Gross income includes business receipts, leasing or transfer of oil and gas rights or assets, and proceeds from disposal of depreciable business capital assets; business expenditure comprises operating costs, finance charges, license and rental payments actually paid, capital expenditure, abortive exploration costs, pre-commencement expenditure, and prescribed site restoration payments. Computation presumes allowance of specified losses and deductions, requires written down value calculations as if depreciation and related allowances were claimed, and limits applicability to non-reconstructed or non-transferred-plant setups, with defined terms for core concepts.