How is Zakat due on a debt that was despaired of, then transformed into the usufruct of a leased land for a period of one year?

Uncollectible debt is not subject to zakat (definition) before its collection, by consensus. After its collection, scholars differ regarding it. Some scholars hold that it is not subject to zakat and a new hawl (lunar year) should begin for it. Others hold that zakat is due on it for all the past years. And still others hold that zakat is due on it for one year only, and this latter opinion is the most preferred (rajih (definition)).

Accordingly, if you mean that the debtor will give you the rent for land for one year, then if you possess a nisab (definition) (minimum taxable amount) from that sum, combined with other funds you own upon which a hawl has passed, then zakat is due on it for one year. However, if the debtor refers you to the land's tenant to collect your debt from the rent due from him, there is no harm in that, and it is subject to zakat after collection for one year, if it reaches the nisab, even by combining it with other assets. If the debtor will give you land to benefit from for one year, there is no zakat on it.