Form SS-8, also known as the "Determination of Worker Status for Purposes of Federal Employment Taxes and Income Tax Withholding," is a form used by the Internal Revenue Service (IRS) to determine whether an individual who performs services for an employer is an employee or an independent contractor. The form is typically used when there is uncertainty or disagreement between the individual and the employer regarding the individual's employment status. The form is filled out by the employer and the individual, and is used by the IRS to make a determination based on the information provided and the applicable laws and regulations.