Addressing a press meet here, Principal Commissioners of I-T, Thane, Sri Krishna and Pramod Kumar said notices were being sent to 18 lakh depositors across the country via e-mails and mobile messages seeking explanation about the source of funds.
These form the deposits during the period of November 9 -December 30, 2016 and include deposits above Rs 5 lakh and some in the range of Rs 3 lakh to 5 lakh, they said.
The time limit given for the reply to notices and compliance is 10 days, Krishna and Kumar said.
In case there is no compliance within 10 days, the I-T department will inspect these "suspicious" accounts and take appropriate action against the depositors, they said.
It has come to notice that in some cases money had been deposited in dormant accounts. Also, in some cases cash had been put in accounts by unknown non-account holders, the I-T officials said.