As only one-fourth of permanent account number (PAN) cards have been linked with Aadhaar cards, the Income-Tax department is preparing a list of those who have not done so and put them under the scanner.

A senior official said, "There are people who must be under-reporting and suppressing income and trying to evade taxes. We are trying to find ways to categorise them in a different basket and put them under scrutiny."

The government had earlier notified 1st July as last date for linking Aadhaar with PAN only for tax filing purposes. From 1 July, income tax payers cannot file returns without quoting Aadhaar or the enrolment number issued at the time of applying for Aadhaar. Recently, the Supreme Court also upheld the government’s decision to make mandatory linking Aadhaar with PAN.

The official said the government will soon come out with a fresh and final date for linking the two identities, beyond which they will start their investigations. Refusal to link the two identities can be considered as "willingly concealing information from tax authorities", he added.

However, the majority of taxpayers across the country have opted to file their tax returns manually, rather than getting an Aadhaar registration done online. Many are reluctant to link PAN and Aadhaar citing privacy. Union Finance Minister Arun Jaitley, speaking at the Income-Tax Department Foundation Day said

"privacy cannot be made an excuse for non-compliance."

A watch is being kept on the nature of expenditure and if it is compliant with the declared income of an assessee. According to government data as on 17 July there were 32.41 crore PAN cards in the country. Of this, only 8.19 crore have linked with Aadhaar.

However, global cyber security experts and several intelligence agencies have warned India to treat the biometric data as a nuclear weapon and to protect it from huge disruptions rather than linking it with everything. India's cyber security chief Gulshan Rai also warned Parliament's finance standing committee last week that India will face increasingly sophisticated "destructive" cyber threats as compared to "disruptive" attacks. The government ~the Centre and states ~ will be he main target of cyber attacks, driven by motives ranging from theft, espionage and data extraction to counterfeiting, he warned.

Also the apex court, in its ruling, referred to instances of leaks of Aadhaar holders' data and emphasised that the government must take steps to curb such leaks. The Supreme Court in its ruling said, "It is important to take proper measures so that confidence is instilled among the public at large that there is no chance of unauthorised leakage of data. Whether it is done by tightening the operations of the contractors who are given the job of enrolment, they being private persons, or by prescribing severe penalties to those who are found guilty of leaking the details, is the outlook of the government."

In a campaign against the Aadhaar scheme linkages, Katherine Albrecht and Liz McIntyre in their report presented to the government titled "SpyChips: How Major Corporations and Government Plan to Track Your Every Move with RFID (radio frequency identification)", said, "It is apparent that RFID and UID/Aadhar projects are going to do almost exactly the same thing which the predecessors of Adolf Hitler did, else how is it that Germany always had the lists of Jewish names even prior to the arrival of the Nazis? The Nazis got these lists with the help of IBM which was in the ‘census’ business that included racial census that entailed not only count the Jews but also identifying them. At the US Holocaust Museum in Washington, DC, there is an exhibit of an IBM Hollerith D-11 card sorting machine that was responsible for organising the census of 1933 that first identified the Jews."