Bloomberg, IRS to Audit 6,000 Companies to Test Employment Tax Compliance, by Ryan J. Donmoyer:

The IRS will audit 6,000 U.S. companies to determine whether they pay all their required employment taxes to fund Social Security and Medicare benefits. The IRS said the audits will provide data for its first statistical analysis since 1984 of how often companies misclassify workers to duck tax obligations, fail to pay taxes on fringe benefits such as personal use of company cars, and improperly pay taxes for company executives. The audits will begin in February, and the companies will be randomly chosen. …

The Treasury Department in 2005 estimated, based on the 1984 IRS data, that companies underpay employer taxes by about $14 billion annually. In particular, federal agencies have raised concerns about whether employers are properly classifying workers as company employees or independent contractors.