What document is used to establish employment eligibility?

The document used to establish employment eligibility is the I-9 form. This form is required by U.S. immigration law and is used by employers to verify the identity and legal work authorization of individuals hired for employment in the United States.

When an employee is hired, they must complete the I-9 form and provide supporting identification documents that confirm their identity and eligibility to work. Employers are responsible for ensuring that this form is completed for each employee, and they must retain these forms for a specified period, as well as make them available for inspection by authorized government officials if required.

The other options pertain to different aspects of employment and taxation. The W-4 form is used for tax withholding purposes, specifically to inform employers how much to withhold from an employee's paycheck for federal income taxes. Form 1040 is an individual income tax return form, and Form 1099 is used to report various types of income other than wages, salaries, and tips, such as payments made to independent contractors. Therefore, these documents do not establish employment eligibility but serve other purposes in the employment and tax processes.