The door is slamming shut on a $50 billion tax loophole used by the superrich

• The US Treasury and IRS are closing a tax loophole used by the über-wealthy.
• They're cracking down on "opaque" business structures that "inflate" deductions. 
• The proposed regulations could generate $50 billion in new tax revenue, the agencies said.

The Treasury and IRS proposed new tax regulations Monday targeting the über-wealthy that they say could result in $50 billion in new tax revenue over the next decade.

The initiative seeks to crack down on "related party basis shifting transactions" — or the use of "opaque business structures to inflate tax deductions," a Treasury press release said.