It is not essential to tell the person who is entitled to zakaah that the money is zakaah

I sent a sum of money to my maternal uncle , and I did not tell him that it is zakaah, because if he knew that it was zakaah he would not take it. So I left this matter between me and Allaah. Is my zakaah valid?.

Praise be to Allaah.

If you gave your zakaah to someone whom you know is entitled to it, with the intention of giving zakaah, then your zakaah is valid and we hope that Allaah will accept it from you. You do not have to tell the recipient that it is zakaah. 

And Allaah is the Source of strength.