The tax gap is comprised of three components -- underreported income, underpayment of taxes and failure to file tax returns at all. 80 percent of gap was due to individuals underreporting their income, while non-filing and underpayment accounted equally for the remaining 20 percent.

The IRS reported that underreporting was mostly linked to understated income, not overstated deductions. The agency also determined that most of the understated income was related to business activities, not wages or investment income.

While these figures may appear shocking, they more or less match the results found in a 1988 study. The numbers are also artificially inflated by individuals that fail to file returns and pay taxes. The IRS is not expected to take any new course of action based on these results.