A top haven for tax cheats that may surprise you: the US

Christensen's group, which campaigns for a global crackdown on tax evaders, says the United States ranks third in the world in financial secrecy, behind Switzerland and Hong Kong but ahead of notorious tax havens such as the Cayman Islands and Luxembourg.

Under a 2010 law, passed after it was learned that the Swiss bank UBS helped thousands of Americans evade U.S. taxes, the United States demands that banks and other financial institutions disclose information on Americans abroad to make sure they pay their U.S. taxes.

In a report last year, the Tax Justice Network complained that "Washington's independent-minded approach risks tearing a giant hole in international efforts to crack down on tax evasion, money laundering and financial crime."

Lawmakers granted business entities greater protection against lawsuits in 2001, hoping to attract more of them and use incorporation filing revenue to raise teacher salaries.

"Nevadans will continue to see nefarious business practices like those reported in the Panama Papers if state officials don't change the laws of incorporation," says Rep. Dina Titus, D-Nevada, even though she voted as a state legislator for the law that protects shell companies that incorporate in Nevada.

Nevada's registered agent industry, which helps businesses incorporate in the state, supports about 1,000 jobs and pumps $110 million into the state economy every year, says the Nevada Registered Agents Association.

Posing as investors who wanted to set up businesses in different places, they kept track of whether the consultants helping them incorporate asked for basic information such as photo IDs or other documents that proved who they were.

The U.S. Treasury Department says it plans to propose regulations requiring foreign-owned "limited liability companies" to get tax identification numbers disclosing the identities of their owners.