Tim Geithner must be lending out his proprietary version of TurboTax!
You are confusing filing an incorrect, and potentially fraudulent return, with filing a correct return that fully declares all your income, but being unable to pay right at the moment. There is nothing illegal about owing money, and the IRS is happy to let you pay in installments at a stiff rate of interest.
It is the people who pay eventually who are actually the most profitable customers.