How is Zakat calculated on salary and saved amounts, especially if part of it is invested in a business facing losses, and is Zakat obligatory on circulating trade capital?

Zakat is obligatory on the sum of savings and invested funds when they reach the nisab and a full year (hawl) has passed over them. They are combined to complete the nisab. Business capital is excluded if it is placed in fixed assets. However, if it is placed in goods and merchandise, it is valued at the end of the year and added to the funds. The profit's hawl follows that of its principal. As for money in an interest-based bank, Zakat is not obligatory on its forbidden interest; rather, one must dispose of it. Zakat is only on the principal amount deposited. However, if the bank adheres to Sharia-compliant dealings, Zakat is obligatory on the profits along with the principal, and their hawl follows that of their principal. It is permissible to unify the Zakat calculation time for all funds to a single occasion, which is easier; thus, you pay Zakat on your money at the same time each year.