Plz solve my doubt

 Do you mean that your client receives rent from the builder due to delay in getting possession of her house constructed by him?

Does she actually stay in rented accomodation and pay rent?

I assume that she stays in her own other house.

In that case the rent received from builder will be fully taxabe as 'income from other sources' as the amount will be in the nature of late possession charges received.

Deduction for Rent paid can be availed under any of the 2 sections:

1. House Rent Allowance received from her employer specifically granted to her which qualifies for exemption under section 10(13A) (subject to certain conditions) The builder is not her employer.

2. u/s 80GG deduction for Rent paid. In this case she should not own any house/ flat which she occupies.

I both above cases, she should actually pay the rent and not occupy her own house.

Take the benefit of HRA and loss from house property. U will make a killing in tax saving.....read article https://www.indiataxfin.com/home-loan-principal-and-interest-income-tax-saving/