The Notice of State Taxation Administration of The People's Republic of China on Printing and Distributing the Measures for Handling Enterprise Income Tax of Real Estate Development Business (Guo Shui Fa [2009] No.31) stipulates: "The income obtained by enterprises from selling unfinished development products shall be calculated quarterly (or monthly) according to the estimated taxable gross profit margin and included in the current taxable income. After the development product is completed, the enterprise shall settle its tax cost in time, calculate the actual gross profit of previous sales revenue, and at the same time, include the difference between its actual gross profit and its corresponding estimated gross profit in the taxable income of the current year calculated by combining this project with other projects. When filing annual tax returns, the enterprise shall issue an adjustment report on the difference between the actual gross profit and the estimated gross profit of the developed products and other relevant materials required by the tax authorities.