Work Authorization Check for Temporary Workers: US Guide

A work authorization check on a foreign temporary worker in the United States has three parts, and they must be done on the right timeline: complete Form I-9 within three business days of the worker's first day (Section 1 by day one), examine original, unexpired documents that establish identity and work authorization, and calendar the expiry date for reverification. Where E-Verify applies, the case must also be created within three business days of the start date. For a staffing firm, these duties belong to the firm as employer, not to the client site.

This article describes the US position as of October 2026. It explains what a check compares: fields, dates and official sources. It does not claim that a check proves a document is genuine. FinCEN and the Bank Secrecy Act, which govern financial institutions, are not the relevant framework here. The Department of Homeland Security, USCIS, ICE and the Department of Justice are.

Who is responsible when a worker is placed by a staffing firm?

The staffing firm is the employer for Form I-9 purposes. Under Immigration and Nationality Act section 274A, it is unlawful to hire, or continue to employ, a person knowing they are not authorized to work, and every employer must verify identity and authorization on Form I-9. The client company that uses the worker is not required to complete the form, but it can face liability as a joint employer, or for knowingly using an unauthorized worker through a contractor.

Civil fines for knowingly hiring or continuing to employ an unauthorized worker are adjusted annually by inflation and run from roughly $700 to over $5,000 per worker for a first offense, with separate paperwork fines of roughly $300 to $2,900 per incomplete or missing Form I-9 (8 CFR 274a.10; ICE Form I-9 inspection fact sheet). A pattern or practice of violations can bring criminal penalties. Check the current adjusted figures on the Federal Register before quoting a number to a client.

Practical consequence: a staffing firm that processes 200 starters a week has 200 separate paperwork exposures a week. Timeliness and completeness are the controls.

Which documents prove a foreign temp worker can work?

The worker, not the employer, chooses which documents to present from the Form I-9 Lists of Acceptable Documents. The employer may not demand a specific document, and doing so can violate the anti-discrimination rules of INA section 274B.

A common misunderstanding: some visa categories authorize work only for a named employer. An H-2B worker, for example, is authorized for the petitioning employer, so a staffing firm cannot simply move that worker to another client unless the petition covers it.

What does E-Verify add?

E-Verify is the federal web-based system run by DHS and the Social Security Administration that checks Form I-9 data against federal records. It is voluntary under federal law for most private employers, but mandatory for federal contractors with the FAR clause and for employers in several states. E-Verify returns "Employment Authorized" or a Tentative Nonconfirmation that the worker may contest.

State laws change the answer for the same worker: Arizona requires E-Verify for all employers, and Florida requires it for private employers with 25 or more employees since July 1, 2023 (Florida Statutes section 448.095). Staffing firms that place workers across states need a state-by-state rule list, not one national policy. California, Illinois and other states also restrict how employers use E-Verify and reverify workers.

An employer enrolled in E-Verify in good standing may use the DHS-approved alternative procedure to examine documents by live video. Employers not in E-Verify must still examine originals in person, or through an authorized representative.

How do you catch mismatches between documents?

Most problems are mismatches, not forgeries. A name entered as "Mohamed Al-Rashid" on the EAD and "Mohammed Alrashid" on the bank form fails a payroll match, creates an SSA no-match letter, or triggers an E-Verify Tentative Nonconfirmation. Date of birth entered with day and month swapped is just as common, as are Social Security numbers with a transposed digit.

A consistent validation run compares the same fields across every document in the file: the I-9 entries, EAD or Green Card, driver's license, bank details, and W-4. Our platform runs this comparison field by field, so the reviewer sees which field differs instead of re-reading each page. See our guide to temp worker document verification at first assignment for the full document list.

What do recruiters and HR staff ask about this?

Questions that recur in recruiter and HR communities are specific.

"The EAD expires next month. Do I stop the assignment?" Not on the day you notice. Reverify in Section 3 of Form I-9 no later than the expiration date, and accept any valid List A or List B plus C document the worker chooses. Some EADs receive automatic extensions under DHS rules, so check the Federal Register notice for the category code.

"Can I ask for a Green Card because the candidate is foreign?" No. Asking for specific documents, or more documents than required, can be discrimination under INA 274B. Offer the list and let the worker choose.

"Do I need to do an I-9 for a one-day assignment?" Yes. Every employee, including temporary and seasonal, needs a Form I-9.

"How long do I keep the I-9?" Three years after the hire date or one year after employment ends, whichever is later, per 8 CFR 274a.2. Limit access to authorized staff, and follow state privacy rules such as the California Consumer Privacy Act, which can apply to applicant data.

How do you manage reverification and expiry dates?

Calendar every document with an expiration date at hire. A practical rule is two alerts: 90 days and 30 days before expiry. Reverification applies only to documents that expire, not to Permanent Resident Cards, and it must not be used on a worker whose documents have no expiry.

For a view across several countries, our staffing agency compliance requirements overview compares document duties by market, and the industry verification pillar guide places this check in the wider picture.

A pre-assignment checklist

1. Have the worker complete Section 1 of Form I-9 no later than the first day.
2. Examine original, unexpired documents from the worker's chosen list.
3. Complete Section 2 within three business days of the start date.
4. Create the E-Verify case within three business days where required.
5. Compare name, date of birth and numbers across all documents.
6. Read visa or EAD conditions against the assignment, employer and hours.
7. Calendar expiry dates and reverification.

For firms placing many workers at once, CheckFile's temporary staffing solution validates completeness, expiry dates and cross-document consistency in one pass. Our security page explains how immigration data is handled and pricing lists the plans.

This article is general information, not legal advice. Rules change; confirm current requirements with USCIS, your state, or qualified counsel. Reviewed by the CheckFile editorial team, October 7, 2026.

Frequently Asked Questions

Does the client company have to complete a Form I-9 for agency workers?

No. The staffing firm that employs the worker completes the form. The client should still require written confirmation that I-9 processes are in place and act if it learns a worker is unauthorized.

Is E-Verify required for staffing firms?

Under federal law it is voluntary for most private employers, but it is mandatory for federal contractors and in several states, including Arizona and, for larger employers, Florida. Check each state where you place workers.

What happens if an EAD expires mid-assignment?

Reverify no later than the expiration date. If the worker cannot present valid evidence of continued authorization, the firm must stop employing them from that date or risk knowing-employment penalties.

Can an F-1 student be placed through a staffing firm?

Only if the student has work authorization such as OPT, and the assignment fits the conditions of that authorization. On-campus and other limited-work rules apply otherwise.

How long must an agency keep Form I-9?

Three years after the hire date or one year after employment ends, whichever is later. Store it separately from the personnel file where possible.