I have a property which brings in rental income.

Answer

You do not pay Zakaat on either the value of the house nor on the rent received. You pay Zakaat after every twelve months on all your cash, gold/silver and stock-in -trade. If at the end of your Zakaat year you have cash left of the rent, then you have to pay Zakaat on that amount. If the rent was used up during the course of the year, then there is no Zakaat payable on it.