Tax exemption is available for the Total Interest charged to your loan account during the FY in which you get possession sucbject to the ceiling. (Interest charded from Apr 08 - Mar 09). Principal repaid during the FY (Apr 08- Mar 09)can be shown as savings under Section 80ccc within the overall exemption (1 lakh). You will not get any benefir for the FY 2007-08, if you are not occupying before 31 Mar 2008.
