How is Zakat to be paid, knowing that there are debts owed to the first and second companies, a debt to your brother that he does not demand until you are able to pay, and you have a shop for sale?

Zakat (definition) is obligatory on the first commercial project and on the loans resulting from it, after the passage of one lunar year from its establishment and the completion of the nisab (definition). Goods prepared for sale are valued at market price at the time Zakat becomes due, with the exception of fixed assets. Promising debts owed by people are added to this, then your due debts are subtracted. If a nisab remains after subtraction, Zakat becomes obligatory. You must hasten to repent for delaying the payment of Zakat if it was due.