A taxpayer shall, in the course of an investigation or reinvestigation conducted by the collection authority, produce account books and related documents of evidence that will prove the amount of his income. Where such account books and documents of evidence are not produced, the collection authority may determine the amount of his 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 collection authority for investigation within the prescribed time limit. Under special circumstances, if it is requested by the taxpayer or deemed necessary by the collection authority, 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 regulation but failed to produce the account books and documents of evidence to prove the amount of his income within a prescribed time limit when notified by the local collection authority conducting an investigation, the local collection authority may determine the amount of his 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, the case it shall be still dealt with according to act.