Two options available:
Option 1) Treating it as gift: Two sections are applicable. One is 56(2)(vi) and second is 64(1)(iv). Former is applicable to your wife and later is applicable to you.
A) Your wife's taxable income: Gift received from relative is exempted u/s 56(2)(vi). Hence the gift received from you is totally exempted from tax in the assessment of your wife's income.
As the gift tax is abolished there is no need to pay gift tax by you.
B) Your taxable income: U/s 64(1)(iv) it amounts to transfer of assets without adequate consideration. Hence if any income accures from the house purchase your wife will be clubbed in your total income. If no income is accrued from the house purchase then nothing will be clubbed in your assessment.
Option 2)Treating it as loan: Two sections are applicable. One is 24(b) and another one is 56. Former is applicable to your wife and later is to you.
A) Your wife's taxable income: Any interest that she may pay to you is deductible under the head income from house property u/s 24(b).
B) Your taxable income: What ever interest she pays to you is taxable in your hands u/s 56.
Rate of Interest: If you treat the amount as loan you can charge interest at any rate. Even you can charge no interest as they amount is your salary savings and you have not borrowed those funds. But it is safe to charge some rate of interest which is not less than savings bank interest rate.
To select Option A or B is tax planning. It depends upon the following 3 major issued:
1. Your income tax slab rate
2. Your wife income tax slab rate
3. Whether the house property generates income
Hope the question is answered