No zakaah is due on wealth that is endowed for the public interest

Wealth that is endowed as a waqf for the public interest such
as the poor, mosques, mujaahideen or orphans is not subject to zakaah,
because it does not have a specific owner. 

Al-Nawawi (may Allaah have mercy on him) said in al-Majmoo’
(5/313): If the livestock is endowed as a waqf for the public interest such
as for the poor, mosques, mujaahideen or orphans and so on, there is no
zakaah on it and there is no difference of scholarly opinion concerning
that, because it does not have a specific owner. End quote. 

Ibn al-Muflih said in al-Furoo’ (2/337): There is no
zakaah on a waqf that is not endowed to a specific person, or to mosques and
schools. 

Al-Bahooti (may Allaah have mercy on him) said in
Kashshaaf al-Qinaa’ (2/171): There is no zakaah on flocks and other
things that are not endowed to a specific person, such as for the needy or
for a mosque and so on, such as a school, because they are not owned by
anyone. End quote. 

The Standing Committee for Issuing Fatwas was asked: Is
zakaah due on wealth that is endowed to the mosques? 

They replied: No zakaah is due on wealth that is endowed as a
waqf for mosques and the like, and there is unanimous agreement on that
(among the scholars), because it does not belong to any specific individual.
End quote. 

Fataawa al-Lajnah al-Daa’imah li’l-Ifta’
(9/412). 

And Allaah knows best.