Therefore, if you pay it to someone in need when he actually needs it, that is well and good. Similarly, giving someone a loan to meet certain needs is a highly commendable act. As Muslims, we do not expect to receive interest on such loans, and actually refuse to take it when offered. Lending to someone in need is an action which cements social relations. Allah rewards us for such actions.
Scholars differ as to when the zakah for loans is paid.
There is no disagreement that the creditor is the one who is liable to pay zakah for the amount of the loan. However, he should pay it out regularly if he knows that the debtor is sound financially and that he will undoubtedly pay his loan. If one has some doubts about being paid back what he has lent, then he commits no sin if he does not include the amount of the loan in his calculation of his liability for zakah. When he is actually paid back, he immediately pays out the zakah due for the amount of the loan, if the date of his payment of zakah has already passed. You can certainly do that if you fear that your uncle might not be able to pay you back for a long time to come.