I.-For each commune, the rate of each of the abatements for property tax on built-up properties provided for in articles 1388 ter, 1388 quinquies, 1388 quinquies A, 1388 quinquies B, 1388 quinquies C, 1388 sexies and 1388 octies is equal to the ratio between:
1° On the one hand, the sum of the products, calculated respectively for the commune and the department, of the tax allowance rate by the tax rate applied in 2020 on the territory of the commune;
On the other hand, the product of the tax allowance rate by the tax rate applied in 2020 on the territory of the department
2° On the other hand, the sum of the property tax rates on built-up properties for the municipality and the department applied in 2020 in the municipality;
II.
II.-For business premises existing on 1st January 2020 and valued in application of article 1498, for the application of I of this article, the allowance rate is equal, for each premises, to the ratio between:
On the one hand, the tax rate applicable to the premises and, on the other hand, the tax rate applicable to the premises.
1° On the one hand, the sum of the products, calculated respectively for the municipality and the department, of the tax base for property tax on built-up properties determined for 2020 on the territory of the municipality, after application of article 1388, by the product of the tax allowance and tax rates applied in 2020;
On the other hand, the rate of tax allowance and tax rate applied in 2020 for the municipality, after application of article 1388, by the product of the tax allowance and tax rates applied in 2020;
On the other hand, the rate of tax allowance and tax rate applied in 2020
2° On the other hand, the product of the sum of the tax rates for property tax on built-up properties for the municipality and the department applied in 2020 multiplied by the municipal tax base for property tax on built-up properties determined in respect of 2020 after application of article 1388 and, where applicable, of 3 of I and III of article 1518 A quinquies.
III.-I and II of I and III of article 1518 A quinquies are applied in 2020.
III -I and II cease to apply to a tax allowance as soon as the municipality decides to modify it in application of articles 1639 A bis or 1640
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However, in the event of application of the first paragraph of this III, the allowances applicable in execution of deliberations taken by the communes and departments as well as those applicable in the absence of deliberations to the contrary adopted by these authorities, in application of articles 1388 ter, 1388 quinquies, 1388 quinquies A, 1388 sexies and 1388 octies, are maintained for their duration and quota initially provided for.