For starters, the $160 billion is spread out over 10 years. $16 billion per year is insignificant given the scope of the federal budget.
However, “many people think CBO’s figure on the cost savings from tax enforcement is a drastic underestimate. The Treasury Department estimates that it would generate $400 billion in revenue, for a net savings of $320 billion, almost $200 billion more than CBO thinks. If Treasury is right, the bill’s effect on the deficit is almost nothing.
The core dispute is over whether, in the face of IRS enforcement, wealthy tax cheats would find new ways to avoid taxes (as the CBO believes), or whether more would actually pay up. Treasury believes the latter, projecting new revenue will come directly (from people forced to pay what they otherwise wouldn’t), and indirectly (as enforcement convinces rich scofflaws to stay on the straight and narrow).”