The research aims to determine the importance of adopting the General Tax Authority in Iraq fair value accounting in determining taxable income by highlighting the failure to apply the historical cost that leads to misleading the users of the financial statements because of the unrealistic and inappropriate information they contain, as well as explaining the role of applying fair value in achieving The basic qualitative characteristics of accounting information in a manner that leads to determining taxable income more closely to justice after being amended according to the applicable income tax law. And analyzing the company's reports so that income is measured according to the fair value on the basis of the IFRS 13, which is subsequently modified according to the applicable income tax law to reach the measurement of taxable income in Iraq as well as the preparation of the Balance sheet In light of this, this measurement is generalized to all Contracting companies listed in the market. The researcher reached a set of conclusions, the most important of which is that the use of fair value accounting in accordance with the IFRS 13 in the contracting sector contributes to providing consistency in accounting measurement and disclosure practices, providing relevance and faithful representation information that is the basis for achieving fairness in tax accounting and recommendations.