Has your client received notice under section 148?
You can challenge the notice as it is time barred in light of section 149 of the Income-tax Act, 1961 (Act). The relevant provision is reproduced hereunder for your ready reference:
149. (1) No notice under section 148 shall be issued for the relevant assessment year,-
(a) ....
(b) if three years, but nor more than ten years, have elapsed from the end of the relevant assessment year unless the Assessing Officer has in his possession books of accounts or other documents or evidence which reveal that the income chargeable to tax, represented in the form of asset, which has escaped assessment amounts to or is likely to amount to fifty lakhs rupees or more for that year.
In your case, since the amount is less than INR 50 Lakhs, your client can consider taking shelter of section 149 of the Act. Even First Proviso to section 149 of the IT Act would also come to your client's rescue.
Your client can either file writ before the HC challenging the reopening or take this ground before CIT(A)