The rebate for int. on home loan depends on the ownership of the house (i.e.whether the joint loanees are co owners or individual owners) and not on who have taken the home loan. You have to claim on the proportion of your ownership. If A and B or joint owners, each can claim Rs.1,50,000/-. In this case, even if father repays the loan for son or son repays for father, the 50% portion can be held as a gift to the other person - G. Suryanarayanan