The income from the sale of a house owned by an individual is a kind of income from transaction in property under Article 9 of the Income Tax Act. Thus, the provision of Article 17-2 of the Enforcement Rules of the Income Tax Act as amended and promulgated by the Executive Yuan on May 30, 1988, with respect to the method to determine the amounts of income from the sale of houses owned by individuals is not contrary to the principle of taxation per legislation. Under said Article, where an individual having sold a house fails to file a tax return or to present documentary evidence, the competent taxing authority shall propose a standard of such income in light of the actual economic conditions and the housing market situation in that year and submit such proposed standard to the Ministry of Finance for approval, and shall, upon approval by the Ministry, determine the income in line with such standard. Accordingly, upon the standard proposed by the Taipei Bureau of the National Tax Administration on the basis of the results of a survey obtained by taking multiple samples of cases where income was earned from the sale of houses during 1987 by individuals residing in the city of Taipei, the Ministry of Finance on June 27, 1988, issued its Directive Tai-Tsai-Shui-Tze No. 770553105, whereby the income from transactions on houses sold by individuals residing in the city of Taipei in the year 1987 was established at twenty percent of the then current value of the particular house as assessed for the purpose of levying the housing tax. The decision of the Ministry of Finance was made by taking into consideration the factors involving year, location, and economic conditions rather than a fixed percentage, and is consistent with the essence of our Interpretation No. 218.We do not find it to be in conflict with the Constitution.