1. If the depreciation is based on the new standards and the future applicable method is used, you don't need to make up the past depreciation. According to the tax law, it is necessary to make supplementary provision, and when it is settled, it should be deducted before tax.

2. With reference to the following detailed rules, elevators can be classified into the third category, which can be amortized for five years and depreciated by the straight-line method. The residual value can be kept at 5%.

unless otherwise stipulated by the competent departments of finance and taxation of the State Council, the minimum depreciation period 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;

(3) five years for utensils, tools and furniture related to production and business activities;

(4) 4 years for means of transport other than airplanes, trains and ships;

(5) three years for electronic equipment.