Article 20 establishes the foundational methodology for calculating Taxable Income. The starting point is the 'Accounting Income' (net profit or loss) from standalone financial statements prepared under accepted accounting standards. This figure is then adjusted for specific items outlined in the law, including unrealised gains/losses, exempt income, reliefs, deductions, and transfer pricing adjustments. The law provides an election for Taxable Persons to account for certain gains and losses on a realisation basis rather than an accrual basis. In any conflict between the law and accounting standards, the provisions of the Decree-Law prevail.