This document discusses various aspects of determining income from business under the tax law, including:
1. Key definitions like permanent establishment, geographical source of income, and thin capitalization.
2. The treatment of income from a permanent establishment of a non-resident and related expenses.
3. The basis of taxation including the method of accounting, treatment of stock, and accrual vs cash basis.
4. Factors to consider in deciding a business income case such as allowable deductions, treatment of assets, depreciation, and bad debts.