The IRS has published the 2017 version of its annual IRS Data Book, which contains statistical information about the IRS and taxpayer activities during the previous year. The IRS Data Book helps illustrate the breadth and complexity of the U.S. tax system. According to the Data Book, during fiscal year 2017 (Oct. 1, 2016 to Sept. 30, 2017), the IRS collected overall more than US$ 3.4 trillion from taxpayers, processed more than 245 million tax returns and other forms, and issued more than $436 billion in tax refunds.

The IRS also audited almost 1.1 million tax returns during fiscal year 2017.  Almost 90% of the audited returns were individual income tax returns. While the percentage of overall returns audited was relatively low at 0.5% overall, the percentages were significantly higher for two types of taxpayers – wealthy individuals and individuals filing international returns. Read More