Zakah on rented property

My brother's employer in Jeddah would like to know that whether or not he should take in to consideration the office buildings and showrooms owns by him for his business purposes while calculating the zakah? If yes, which amount he should take into consideration (purchase price or market value).

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

There is a disagreement among scholars over the rule of the Zakah of the rented, leased or occupied buildings, shops, flats, apartments, cars and boats which are prepared for lease.  Some scholars believe that the value of those things themselves is estimated at the end of every year and their Zakah is calculated like that of commodities and trade goods.  Others believe that Zakah is only due on the returns of these things on the time of receipt with no need to wait for a year to pass after the collection.

A third group of scholars believe the proceeds from these leased things are added to other things that are subject to Zakah and if they all reach Nisaab, then the person has to pay the Zakah after passing one complete lunar year.  This is the opinion of the majority of scholars from different schools of thought in Fiqh.  So, the Zakah is then due on the returns of these leased things if these returns reach the Nisaab by themselves otherwise the Zakah is due on them added to other properties like currencies, and trades commodities.

However, if these buildings are not for rent or if they are offices or stores of the owning company, then no Zakah is due on them because they are properties that are for private use.

Allah knows best.