Genesis to 1943

• The W-9 Form is a bureaucratic result of the IRS implementing tax withholding authority provided in the Current Tax Act of 1943. This congressional set of statutes was marketed in a series of political statements convincing the public that tax payment was a patriotic duty, so withholding ensured everyone participated.
  
  

Expansion

• The IRS and political policy work in the late 1970s and 1980s expanded withholding to independent contractors as a catchall for tracking other payments made outside of payroll. IRS personnel were instructed by internal policy to use cross-referencing systems to find unreported, taxable income in taxpayers.
  
  

1983 and Subsequent Updates

• According to the Los Angeles Times, the IRS introduced the W-9 in 1983 as part of further withholding reporting expansion. Multiple variations were approved since that time. For example, the IRS updated the W-9 in October 2007 providing detailed options for limited liability companies to provide their status. The form was also changed to report citizenship status of the filer.