The high volatility trading in the stock market is now fuelling tax authorities to keep a closer eye on stock market transactions. While the ministry is satisfied with the collections from securities transaction tax (STT) so far, it wants to ensure that there is no under reporting or non-reporting of such transactions, leading to tax evasion.Tax authorities are now looking at the possibility of using audit trails of STT collection to check such instances. "The audit trail from STT collections can be used to check adjustments in the stock market," an official pointed out.The STT data can also be matched with the computer aided scrutiny system (CASS) to identify offenders who are trading in the stock market but not filing returns or under reporting in the returns, he added. In such cases, the income tax department can send scrutiny notices and check any evasion of tax.Tax authorities are yet to take a final call on whether they will follow through with this measure as STT collections have witnessed record growth so far this fiscal.STT collections till December 15 have registered a 75% growth to stand at Rs 5,895 crore. The government now expects STT collections for the entire fiscal to total about rs 7,500 crore with the heavy-duty action on the stock markets. Direct tax collections too have risen by over 40% and have crossed the Rs 2,00,000 crore mark. They are expected to amount to Rs 3,00,000 crore by the end of the fiscal.The average daily trading on the Bombay Stock Exchange and the national Stock Exchange has gone up to about Rs 20,000 crore. The 30-share Sensex of the BSE has gained over 5,000 points this fiscal and closed at 20,216.72 points on Thursday.Increasing tax compliance has been the main focus of tax authorities this fiscal, with measures aimed at all sections of taxpayers, including stock exchange transactions. Earlier during the year, tax authorities had added 10 more categories of non corporate taxpayers for mandatory scrutiny. This had included all cases of commodity brokers as well as their sub-brokers earning brokerage of Rs 1 crore or more, whose returns would be compulsorily scrutinised along with stock brokers – www.financialexpress.com