Zakah on loans

Should I give Zakah for money that I lent to friends? I know that I'll get this money back but I don't know exactly when.

Praise be to Allah, the Lord of the World; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
If your friends acknowledge that they owe you the money you lent them and if they are able to pay you back, then you have to pay the Zakah of what they owe you along with your other properties whenever a year passes on that money. But if your friends are "down and out", or if they deny having taken any money from you, then you are not obliged to pay the Zakah of this money before you actually get it in your hand. When you get that money, you should pay its Zakah for one year only.
Allah knows best.