It also asked the tax payers to voluntarily come forward and disclose their true income details by filing revised returns.
"Investigations conducted by the department in recent months in about 150 cases in Mumbai and 39 in Pune have led to detection of bogus bills of Rs 6,500 crore and Rs 722 crore, respectively," the I-T Department said in a statement here.
A large number of taxpayers have obtained "bogus/non- genuine bills for purchases/expenses from a few hawala dealers and used such bills to suppress taxable income," it said.
It has checked up on the bills with the value-added tax and sales tax authorities in Maharashtra to establish that the bills are fake.
The department warned necessary action is being taken in such instances.
"Taxpayers are informed that if they have availed of such bogus/non-genuine bills for purchases/expenses, they may come forward voluntarily and disclose the correct state of affairs by filing their returns/revised returns duly backed with payment of requisite taxes before specific detection by the department," it added.
Forced by the hardships to contain fiscal deficit at the targeted levels because of falling growth numbers, the Union Finance Ministry has been lately looking at avenues to expand revenue collections and warning of stringent consequences against tax dodgers.