The IRS SS-8 Program allows either a Company or a Worker to request that the IRS evaluate and determine whether the Worker is an employee or an independent contractor for Federal/IRS Purposes. The resulting Determination by the IRS SS-8 Unit is just the SS-8 Unit's "opinion" (not an actual audit!).
The IRS uses a Questionnaire called the IRS Form SS-8 (Determination of Worker Status for Purposes of Federal Employment Taxes and Income Tax Withholding) to determine when a particular "worker" is an independent contractor and when the "worker" is an employee.
Over the years, I've had an increasing number of phone calls from company owners who have received in the mail a disturbing and unwelcome letter from an IRS SS-8 Unit, usually located in Holtsville, New York.
The Answers to the Top Ten Employer Questions