The Income Tax returns filed after November 8 last year were scrutinised against their earlier tax compliance following which these cases were detected, he said.
"We are taking action in these instances," Chandra told reporters on the sidelines of an event to mark the 157th Income Tax day here.
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He said that after the first phase of 'Operation Clean Money', it was found that some assessees did not report about all their bank accounts to the taxman.
Under the Operation Clean Money, the I-T department is contacting those whose bank account deposits were seen to be suspicious post the note ban.
"We have found that they (assessees) have got more accounts...They have given less accounts in their replies (to the department). We have now informed them through email and want their response over our website," he said.
The Income Tax boss also said that India has an entry rate tax at 5 per cent of the income which is one of the "lowest" across the globe.
"It is a very reasonable rate of taxation....I do not think we can lower it at present," he said.
Talking about the department's action under the newly enacted Benami Transactions Act, Chandra said the taxman has made attachments worth Rs 840 crore in 233 cases till now.
"We have found that many shell companies are owning such (benami) properties. Action will be taken," he added.
The demonetisation of Rs 1,000 and Rs 500 currency notes was announced by Prime Minister Narendra Modi on November 8 last year.