In 2008, the IRS initiated efforts to curb the use of offshore accounts to evade taxes. This paper uses administrative microdata to examine the impact of enforcement efforts on taxpayers’ reporting of offshore accounts and income. We find that enforcement caused approximately 50,000 individuals to disclose offshore accounts with a combined value of about $100 billion. Most disclosures happened outside offshore voluntary disclosure programs, by individuals who never admitted prior noncompliance. Disclosed accounts were concentrated in countries often characterized as tax havens. Enforcement-driven disclosures increased annual reported capital income by $2-$4 billion, corresponding to $0.6-$1.2 billion in additional tax revenue.