The Treasury Inspector General for Tax Administration today released Currency Report Data Can Be a Good Source for Audit Leads (2010-30-104):

Individuals who fail to file required returns or underreport their income can create unfair burdens on honest taxpayers and diminish the public’s respect for the tax system. While currency reports may be commonly associated with money laundering, TIGTA identified a number of individuals who have enough cash to engage in currency transactions totaling at least $20,000, but did not file tax returns even though they appeared to have a filing requirement.

A number of other individuals engaged in similar currency transactions filed tax returns, but reported income that does not appear sufficient to cover their basic living expenses.