Ayyub bin Abi Tamimah al-Sakhtiyani (may Allah have mercy on him) said that Umar bin Abd al-Aziz (may Allah have mercy on him) wrote, concerning wealth that some governors had seized, that it should be returned to its owners and its zakah taken for the years that had passed. Then, after that, he sent another letter saying that only a single zakah should be taken from it, because it was dimar; and this means wealth whose recovery is not hoped for.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7626