(CNN) - The U.S. is owed billions of dollars in back taxes, and Americans aren't paying up.
Every year the IRS says it faces an estimated $458 billion "tax gap" - income taxes that are owed, but not paid.
The IRS said it manages to recapture about $52 billion a year through enforcement efforts like tax audits.
Most Americans do pay up every year. Voluntary compliance is at 82 percent.
The IRS attributes the shortfall to under-reporting, underpayment and the remaining 18 percent who just don't pay.
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