Tax exemption is available on both as under:
Assuming presently you don't have a owned property,
Pre-construction interest: acumulate till yr prior to yr of completion of construction.
Post construction interest: can be claimed u/s 24b
Total interest post construction: 1/5 of pre-con int(for 5 yrs)+post con interest, upto a max of 2L p.a.
Further, if new house purchased is Self occupied, then the constructed HP is DLOP interest on which is available for exemption without limit. Interest on new house will be restricted to 2L p.a.
Deduction for principal payment for both houses combined is available upto a max of 1.5L p.a u/s 80C(assuming no other investments under that sec).
Hope this helps.
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