All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Partnership in trade has no impact upon paying Zakah. It is obligatory upon each partner separately if a lunar year elapsed after his money reached the Nisaab to pay the Zakah of his money including his profits from trade in addition to the money or other trade commodities he owns outside the partnership.
He should know his share of the debt that belongs to him in the partnership and deduct it from the money upon which Zakah is obligatory. Zakah should be paid for the sum remaining after repaying the debt because the majority of scholars adopt the opinion that being indebted releases from the obligation of Zakah in case of hidden wealth which means gold, silver, cash and trade commodities.
Thus, it is obligatory upon each of the partners to pay Zakah for his share of the partnership if it reaches the Nisaab and an entire lunar year elapsed on it along with deducting his share of the debt in hidden wealth. They should pay Zakah for the remaining sum after deducting the value of the debt. The Nisaab of the present paper money is twenty Mithqaals of gold which equals, in present measurements, about eighty-five grams.
Allaah Knows best.