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Form I-9 Basics: How US Employment Eligibility Verification Works

Nearly every new US employee fills one of these out in their first days on a job, yet many people never fully understand what it actually verifies.

It verifies identity and authorization to work, not tax status

Form I-9 exists to confirm both who a new employee is and that they are legally authorized to work in the United States. It is a distinct requirement from tax forms like the W-4, which instead determine how much income tax is withheld from pay.

Section 1 must be completed by the employee's first day of work

The employee fills out Section 1 with their own identifying information and attests to their work authorization status no later than their first day of actual employment, though it can be completed earlier once a job offer is accepted.

Section 2 must be completed within three business days of starting

The employer, or the employer's authorized representative, must physically examine the employee's original identity and work-authorization documents and complete Section 2 within three business days of the employee's first day of work for pay.

Employees choose from List A, or List B plus List C

A List A document (like an unexpired US passport) establishes both identity and work authorization on its own. Alternatively, an employee can present one document from List B (establishing identity, like a driver's license) together with one from List C (establishing work authorization, like a Social Security card).

The employee chooses which acceptable documents to present

Employers are not allowed to demand a specific document or combination of documents from an employee, or refuse otherwise-acceptable documents that reasonably appear genuine, as long as the employee presents a valid combination from the official lists.

Employers must retain I-9s for a set period, even after termination

Completed I-9 forms generally must be retained for three years after the date of hire, or one year after employment ends, whichever date is later β€” meaning the form often has to be kept well beyond the employee's last day.

E-Verify is a related but separate, additional system

E-Verify is an online system that electronically cross-checks I-9 information against government records; it is not required for every US employer, though federal contractors and, in some states, most or all employers are required to use it β€” requirements vary by state and can change.

Some employees need reverification later

If an employee's original work authorization document had an expiration date, the employer is generally required to reverify that authorization before it expires, using the dedicated reverification section of the current form rather than starting an entirely new I-9.

Examples from each list

List A includes a US passport, a permanent resident card, and an employment authorization document. List B includes a driver's license or state ID and a school ID with a photograph. List C includes an unrestricted Social Security card and a US birth certificate. Which combination to present is the employee's decision.

Receipts for lost, stolen, or damaged documents

If an employee cannot present a document because it was lost, stolen, or damaged, a receipt showing they applied for a replacement can serve as temporary proof. The employee must then provide the actual document within 90 days.

Very short jobs have a shorter deadline

If the employee will work for fewer than three business days, Section 2 is due by the end of the first day of work, not within three business days.

Rehires within three years

If a former employee returns within three years of the date the original I-9 was completed, the employer can use Section 3 to record the rehire and, if needed, new work-authorization information instead of filling out a fresh form. After three years a new form is generally required.

Remote document examination is possible only under a specific procedure

Employers enrolled in E-Verify and in good standing may use an alternative procedure authorized by the Department of Homeland Security to examine documents by live video and review copies, and they must check the box in Section 2 that says they did so. Employers not eligible for the procedure must examine original documents in person.

Independent contractors do not complete I-9s

The requirement applies to employees. Genuine independent contractors are not covered, but misclassifying a worker to avoid paperwork can create legal problems, so the worker's actual relationship with the company is what counts.

Employers cannot treat workers differently because of citizenship or national origin

Federal law prohibits asking for more or different documents based on a person's appearance, name, or perceived immigration status. The Justice Department's Immigrant and Employee Rights Section handles complaints.

Use the edition currently posted by USCIS

USCIS publishes the form with an edition date and sets the dates through which each edition may be used. As of the USCIS I-9 page, the 01/20/25 edition is the current one, and employers should check that page rather than using an old saved copy.

Why this form exists separately from tax paperwork

Form I-9 and tax forms like the W-4 serve entirely different government purposes β€” one confirms legal eligibility to work at all, administered under immigration-related employment law, while the other determines payroll tax withholding. New employees often fill both out in the same onboarding packet, which is a common source of confusion about what each one actually does.

The document lists exist to standardize a subjective process

Because acceptable identification varies so much by state and by individual circumstance, the official List A, B, and C system gives employers a defined, limited menu of documents to check rather than leaving acceptability up to case-by-case judgment, which also protects employees from being asked for documents beyond what the law actually requires.

Where employers most often make mistakes

Typical errors found in audits include a missing signature or date, no document title or number in Section 2, a date of hire that does not match payroll records, Section 1 completed late or by the employer without the employee, and old or outdated form editions. Most are simple clerical problems that regular internal checks catch. Employers also should not ask for I-9 documents before a job offer is accepted, because the form is for confirming eligibility after hire.

Practical filing tips

Keeping I-9s in a file separate from the personnel record makes them easier to produce during an inspection and avoids exposing sensitive identity documents to people who do not need to see them. Employers can complete and store I-9s electronically if the system meets federal standards for integrity and audit trails. Calendar the retention date for each form, and calendar the expiration date for employees with limited work authorization so reverification happens on time. This is general information, not legal advice.

Frequently Asked Questions

Is Form I-9 the same as a tax form?

No. Form I-9 verifies identity and work authorization; it is unrelated to tax withholding, which is instead handled by separate forms like the W-4 for federal income tax purposes.

Can an employer ask for a specific document, like only a passport?

No. As long as an employee presents a valid, acceptable combination of documents from the official lists, the employer cannot require a specific document or reject genuine-looking, acceptable documents in favor of a preferred one.

How long does an employer have to keep completed I-9 forms?

Generally three years after the date of hire, or one year after the employment relationship ends, whichever of those two dates comes later.

Is every employer required to use E-Verify?

No, not universally β€” E-Verify is mandatory for many federal contractors and, in some states, for most or all employers, but requirements vary by state and have changed over time, so it is worth checking current state-specific rules.

What is Section 3 of the form for?

Section 3 is used to reverify work authorization when a document expires and to record rehires within three years. It saves the employer from starting a new form in those cases.

Do U.S. citizens ever need reverification?

No. Reverification applies only to employees whose work authorization has an expiration date. Citizens and lawful permanent residents with permanent documents do not need it, and List B identity documents are not reverified.

Can an employer fill out Section 1 for me?

Section 1 belongs to the employee, who must complete and sign it. A preparer or translator may help and must sign the certification, but an employer who fills in the employee's information without the employee's participation risks errors.