A statement said more than eight billion euros of value added tax were also not returned to state coffers, adding that action had been taken against more than 12,000 people during the past year for fraud.
Twenty-one billion euros of the undeclared earnings were stashed overseas, mainly in tax havens, it said.
According to estimates, Italy loses between 120 and 150 billion euros annually due to tax fraud.
Italy has a public debt of around 1.9 trillion euros or 120 percent of gross domestic product, one of the highest levels in the 27-nation European Union.
The government is not relying on hi-profile raids alone and has pushed for a greater role for Equitalia — a tax collection agency that is widely hated for its strongarm methods and has been the target of a string of attacks.
Last month the deputy head of the agency was sent a letter bomb by an anarchist group which blew up in his face. The populist Northern League party has also gone on the offensive, warning against “a tax police state”.
Prime Minister Mario Monti came to power in November calling for a radical change to defend “honest taxpayers”.
“It’s unacceptable that workers have to make sacrifices while a major chunk of wealth is not taxed,” Monti has said.