Hello,
Joint holders can claim the maximum tax benefits individually. This means each holder can get a tax rebate of Rs. 1.50 lakh for principal repayment under Sec 80C and Rs. 2 lakh for interest payment under Sec 24.
The tax benefits are applied according to the proportion of the loan taken by everyone involved in the joint loan. For e.g. if the ratio of ownership is 70%:30% then the loan amount of 50 L will be split as 35 L and 15 L respectively and interest/principal applicable to the respective amounts will be taken into account for each individual taking the loan. For claiming your tax, it is best to procure a home sharing agreement, detailing the ownership proportion in a stamp paper, as legal proof for ownership.