Tax base in practice: For industrial enterprises, income taxes are generally assessed on the __________.

Introduction / Context:
Understanding what constitutes the tax base is key for after-tax economic evaluations, NPV, and IRR calculations. In general, corporate income taxes are assessed on taxable income (commonly referred to here as total income after allowable deductions).

Given Data / Assumptions:

• Standard corporate tax regimes are considered.
• Gross earnings and costs are accounted to arrive at taxable income.
• Terminology in the options uses “total income” to denote the tax base post-deductions.

Concept / Approach:
Taxable income is the result of gross earnings minus allowable deductions (operating costs, depreciation, interest where applicable, and other deductible items). Taxes are not levied on gross earnings, on costs, or on fixed costs in isolation. Thus, the correct conceptual selection is the enterprise’s total/taxable income.

Step-by-Step Solution:

Verification / Alternative check:
Check any standard income statement leading to “income before tax” as the base for tax calculation.

Why Other Options Are Wrong:

Common Pitfalls:
Equating “revenue” with “taxable income.” Always consider depreciation and other deductions.

Final Answer:
total income