Officials said an authorised representative of Anita Singhvi submitted her response to the tax department yesterday.
She was asked to explain how much she had paid in cash and how much through cheque to purchase the valuables and jewellery from Modi's firms a few years back.
It was not immediately known as to what her explanation was.
Abhishek Manu Singhvi had earlier refuted the allegations made against his family and described the I-T action as "harassment" being meted out to him as he belonged to an opposition political party.
The department yesterday expanded its probe into the alleged bank frauds at the Punjab National Bank (PNB) and involving the Rotomac pens company as it attached 144 bank accounts and fixed deposits (FDs) of the Gitanjali Gems group, promoted by Mehul Choksi.
The total deposits in these accounts and FDs was Rs 20.26 crore, officials said.
It also attached a dozen bank accounts of the Rotomac pens group as part of its tax evasion probe against it. The tax demand against the group, whose owner Vikram Kothari and son Rahul were arrested by the CBI on Thursday, was about Rs 106 crore, they added.
Fourteen bank accounts and four immovable assets of the group have already been attached by the department.
The attachment of assets action, the officials said, was undertaken to "recover outstanding tax demands" from the accused.
The Kanpur-based group is being probed by the CBI and the Enforcement Directorate (ED) in connection with an alleged bank loan fraud of Rs 3,695 crore, sanctioned by a consortium of seven banks.
Modi, his uncle Choksi and others are being investigated by the CBI, ED and the tax department after a bank fraud recently came to light, following a complaint by the PNB that they allegedly cheated the nationalised bank to the tune of Rs 11,400 crore, with the purported involvement of a few employees of the bank.
The CBI and the ED have registered two FIRs each to probe these instances against Modi and Choksi.
Both of them are said to have left the country before the criminal cases were lodged against them.