Offshore Tax Evasion: IRS Has Collected Billions of Dollars, but May be Missing Continued Evasion, Report to Congressional Requesters [open pdf - 4MB]
From the GAO (Government Accountability Office) Highlights: "Tax evasion by individuals with unreported offshore financial accounts was estimated by one IRS [Internal Revenue Service] commissioner to be several tens of billions of dollars, but no precise figure exists. IRS has operated four offshore programs since 2003 that offered incentives for taxpayers to disclose their offshore accounts and pay delinquent taxes, interest, and penalties. GAO [Government Accountability Office] was asked to review IRS's second offshore program, the 2009 OVDP [Offshore Voluntary Disclosure Program]. This report (1) describes the nature of the noncompliance of 2009 OVDP participants, (2) determines the extent IRS used the 2009 OVDP to prevent noncompliance, and (3) assesses IRS's efforts to detect taxpayers trying to circumvent taxes, interests, and penalties that would otherwise be owed. To address these objectives, GAO analyzed tax return data for all 2009 OVDP participants and exam files for a random sample of cases with penalties over $1 million; interviewed IRS Offshore officials; and developed and implemented a methodology to detect taxpayers circumventing monies owed. […] Among other things, GAO recommends that IRS (1) use offshore data to identify and educate taxpayers who might not be aware of their reporting requirements; (2) explore options for employing a methodology to more effectively detect and pursue quiet disclosures and implement the best option; and (3) analyze first-time offshore account reporting trends to identify possible attempts to circumvent monies owed and take action to help ensure compliance. IRS agreed with all of GAO's recommendations."
Government Accountability Office: http://www.gao.gov/