What is the correct method for a sole proprietorship that designs and manufactures ornamental glass to pay Zakat, and is Zakat paid on net profits, capital, or owner's equity, and is the tax paid to the Zakat and Income Department considered a form of Zakat?

Zakat is obligatory on industrial and commercial companies for trade goods, but not on machinery, equipment, and buildings used for operation. Zakat is calculated at 2.5% of the value of goods prepared for sale, cash, and collectible debts. Profits from the sale of glass are subject to zakat along with the capital. As for installation profits, zakat is due after a full year (hawl) has passed since their receipt, and it is permissible to pay the zakat for all profits in advance. There is no zakat on profits spent during the year. The hawl for trade goods is calculated upon the completion of the hawl of the original capital with which they were purchased. If taxes are paid before the end of the hawl, no zakat is due on them. However, if they are paid after the completion of the hawl, it is more cautious to pay zakat on them. It is not permissible to count taxes as part of zakat because the expenditures of zakat are legally specified. Zakat for previous years must be paid, as ignorance does not waive its obligation.