[Flashman_at_the_charge]

How would that work, considering the "underground economy" consists of unreported transactions?

People who benefit from the underground economy eventually end up purchasing legitimate goods and services. For example the dope dealer with the brand new SL500 or the illegal immigrants enjoying a day out at Disney.

[TommyDale]

Spending money earned illicitly in the underground economy doesn't help the tax revenue stream. There needs to be a way to assess those people who have been freeloading from the tax system.