article 36 of the accounting system for enterprises stipulates that an enterprise shall reasonably determine the expected service life of fixed assets according to their nature and consumption mode. Article 61 of the "Regulations for the Implementation of the Enterprise Income Tax Law of the People's Republic of China" stipulates: Unless otherwise stipulated by the competent departments of finance and taxation of the State Council, the minimum period for calculating depreciation of fixed assets is as follows: (1) 21 years for houses and buildings; (2) Aircraft, trains, ships, machinery, machinery and other production equipment, 11 years; (three) appliances, tools, furniture, etc. related to production and business activities, for 5 years; (4) 4 years for means of transport other than airplanes, trains and ships; (five) electronic equipment, for 3 years. If the depreciation period determined by the enterprise is equal to or greater than that stipulated in the tax law, the depreciation expense can be deducted before tax; If the depreciation period determined by the enterprise is less than that stipulated in the tax law, the depreciation accrued more than that calculated according to the tax law shall be subject to tax adjustment. three