To trace the source of money and detect possible tax evasion, the income tax department is investigating 60,000 high-value transactions that date back to 2004-05.

These transactions are based on the Annual Information Reports (AIR) filed by entities like banks, mutual funds and companies.

Saying that the cases had been selected under a computer-aided scrutiny selection process, official sources told Business Standard that the investigations are likely to be complete by December 2007.

The 60,000 cases were selected from a pool of 18.7 lakh (1.87 million) high-value financial transactions worth Rs 13,99,890 crore (Rs 13,998.90 billion) captured under AIR for 2004-05.

Interestingly, the number of high-value transactions reported fell by 2.86 lakh (286,000) in 2005-06, though their value shot up by Rs 9,25,631 crore (Rs 9,256.31 billion) to Rs 23,25,521 crore (Rs 23,255.21 billion) in that year.

The category of transactions tracked under AIR include cash deposits of Rs 10 lakh (Rs 1 million) and above, credit card bills of Rs 2 lakh (Rs 200,000) or more, mutual fund investments of Rs 2 lakh and above, investments of Rs 2 lakh or more in a company's bond issue, acquisition of a company's shares worth Rs 1 lakh (Rs 100,000) or more, purchase of immovable property valued at above Rs 30 lakh (Rs 3 million), and investment of Rs 5 lakh (Rs 500,000) and above in bonds issued by the Reserve Bank.

The AIR initiative was launched in 2004-05 to identify tax evaders. The information collected in 2004-05 was submitted for assessment in 2005-06 but is being scrutinised only in this financial year.

With tax rates slowly being reduced, the focus of the government machinery is now on improving tax compliance to broaden the tax base and sustain revenue growth.