I specifically mentioned in my 1st first post that I am not dealing with the income under the hand of Mr.Z or his son because the OP asked in whose income the interest income is to be clubbed.
The clubbing provisions (in this case) will be applicable at two stages.
- In the hands of Mr.X. [§ 60]
- In the hands of Mr.Z. [§ 64(1A)]
§ 64(1A) would be applied when we will be computing the income of Mr.Z. The OP asked in whose income the interest income is to be clubbed, where § 60 is applicable.]
Undoubtedly, the interest income would be clubbed in the hands of Mr.X only.
However, when the amount of interest is credited to Mr.Zs son. This transaction can be treated as in income of minor which would be clubbed in the hands of his parent, let's presume father in this case.
You might be thinking that on the same amount, the tax is being 2 times, once by Mr.X and another time by Mr.Z. However, it is pertinent to note that there are two assessees. And you can find such a treatment at multiple places in the Income Tax Act.
Here, the amount of interest is around 50k, which is the maximum amount not liable to be taxed if its a gift u/s 56(2)(X)(a) [as cited below]
[56(2) In particular, and without prejudice to the generality of the provisions of sub-section (1), the following incomes, shall be chargeable to income-tax under the head "Income from other sources", ]namely :—
(x) where any person receives, in any previous year, from any person or persons on or after the 1st day of April, 2017,—
(a) any sum of money, without consideration, the aggregate value of which exceeds fifty thousand rupees, the whole of the aggregate value of such sum;]
Hence, the said credit may be treated as a gift from Mr.X to his friend Mr.Z (or his son)
If Mr.Zs total income from under the said sub-clause exceeds more than 50,000 then the entire amount becomes taxable u/s 56(2)(x)(a). Otherwise, if the income under the said sub-clause is upto 50k, then nothing from that is taxable under the hands of Mr.Z
Let me know if there's any iota of doubt.