Praise be to Allah.
Zakaah is one of the pillars of Islam. If a person does not do it because he does not believe that it is obligatory, the ruling should be explained to him and if he persists, then he is a kaafir, and the funeral prayer cannot be offered for him and he cannot be buried in the Muslim graveyard. But if he does not pay zakaah because he is stingy, but he believes that it is obligatory, then he is a sinner who is guilty of a major sin and he is a wrong doer, but he is not a kaafir. Therefore he should be washed (ghusl) and the funeral prayer should be offered for him if he dies in this state, and his case will be decided on the Day of Resurrection.