Income Tax Act Article 83

A taxpayer shall, in the course of an investigation or recheck conducted by the tax authority, provide account books and related documents of evidence that will prove the amount of his/her/its income. Where such account books and documents of evidence are not provided, the tax authority may determine the amount of his/her/its income based on the available taxation data or the profit standard of the same trade concerned.The taxpayer shall present the account books and documents of evidence as referred to in the preceding paragraph to the tax authority for investigation within the prescribed time limit. Under special circumstances, if it is requested by the taxpayer or considered necessary by the tax authority, an investigation at the taxpayer's place of business may be made by a designated official.Where a taxpayer has already filed the income tax return in accordance with the established regulations but failed to provide the account books and documents of evidence to prove the amount of his/her/its income within a prescribed time limit when notified by the tax authority conducting an investigation, the tax authority may determine the amount of his/her/its income based on the available taxation data or the profit standard of the same trade concerned. If more taxation data are subsequently discovered upon investigation, such taxation data shall be still dealt with according to law.