Stop Tax Haven Abuse Act

[AI summary unavailable — showing source text] Stop Tax Haven Abuse Act - Amends Internal Revenue Code provisions relating to tax shelter activities to: (1) establish legal presumptions against the validity of transactions involving offshore secrecy jurisdictions (i.e., foreign tax havens identified in this Act and by the Commissioner of the Internal Revenue Service); (2) impose restrictions on foreign jurisdictions, financial institutions, or international transactions that are of primary money laundering concern or that impede U.S. tax enforcement; (3) increase the period for Internal Revenue Service review of tax returns involving offshore secrecy jurisdictions; (4) require tax withholding agents and financial institutions to report certain information about beneficial owners of foreign-owned financial accounts and accounts established in offshore secrecy jurisdictions; and (5) disallow tax advisor opinions validating transactions in offshore secrecy jurisdictions. Amends the Securities Exchange Act of 1934 and other federal enactments to impose a penalty for failure to disclose holdings or transactions involving a foreign entity. Requires the Secretary of the Treasury to publish a final rule requiring unregistered investmen…