Dear freind, On the basis of information you have shared of your client, following would be the calculation of House Property he is holding in my opine:
In the Income tax law there is a provision that if a person is holding a house which he occupy for his residence purpose or not able to occupy for residence purpose due to his employment or business and lived in the house which is not belong to him i.e., lived in rented house. In that case Annual value of property would be taken as NIL. (Sec 23(2) of Income tax act 1961)
The case you have mentioned of your client would fall in the above provision, as your client due to somehow reason not able to lived in his house instead lived in the rented house. AND also if mother staying in his house would be lead as that he himself occupy for residence purpsose since a person occupy include occupy his family too.
So in the instant case client's house would not be considered deemed let out and it annual value would be NIL in my opine.
Further he would be also eligible for the deduction on the INTEREST PAID on loan taken on home assuming its taken for its acquisition , renovation or construction up to Rs. 30000/150000 as the case may be. (U/s 24 (2) proviso 2)
Furhter more, he would also entitled for deduction u/s 80C of PRINCIPAL amount paid in annual installment up to 1Lac. subject to all the condioned mentioned in 80C satisfied assuming all are satisfied in our case.
Hence calculation would be as
Income under the head of property
Annual value of property: NIL
Less deduction u/s 24(2): (150,000)
Total (Loss) in the the house property head : (150,000)
This loss can be set off with any other head income and if not able to set off in current year can be carried forward and set off with income of House property for 8 years.
Hope above clarify and serve the purpose.
Thanks