IRS policy encourages non-filers to make a voluntarily disclosure by filing the delinquent returns, and thus bring themselves current on any outstanding filings and voluntarily report the associated income tax, penalties and interest due.
The IRS’s official written policy is that where non-filers voluntarily come forward before an IRS investigation or examination has begun, have only income from legal sources, file an accurate tax return and pay (or make arrangements to pay) their tax, they will not be referred for criminal prosecution for failure to file.