Is zakat paid on the nisab of the individual who is a business owner or on the nisab of a business or property?

In a business the nisab is measured by the business owner’s nisab, not on the business or the property. So if there are two business partners, they pay zakat on their respective nisab not on the business or property aggregate. The Shafi’i school calculates nisab on the basis of the entire business or property, even if individual partners do not qualify for nisab; the Maliki school exempts partners who have been with the business or shared in the property for less than one lunar year and nisab is not triggered at both ends of the year or who do not qualify for nisab.