Contractor onboarding checklist for staffing agencies

A contractor onboarding checklist for a staffing agency covers the paperwork a worker has to complete between the offer and the first shift: Form I-9 to confirm they can legally work in the US, a W-4 or a W-9 depending on how the worker is paid, E-Verify if the agency or client requires it, and the policies and timesheet setup the assignment needs. None of this is about culture or tools — it is the compliance floor a staffing agency has to clear before a worker can start getting paid.

This is a different checklist from new hire onboarding checklist, which is a hiring manager's plan for a direct employee's first weeks — introductions, goals, tools. It is also narrower than Form I-9 timing in hiring, which goes deep on the I-9 deadline rules alone. This page is the fuller checklist: I-9 plus the tax forms, E-Verify and the operational setup around them.

W-2 temp employee or 1099 independent contractor

Most workers a staffing agency places are W-2 employees of the agency, even though they work on-site for a client. The agency runs payroll, withholds tax, and collects a Form W-4. A true independent contractor — someone the agency pays as a business, with no withholding, who invoices and controls how the work gets done — completes a Form W-9 instead, and gets a 1099 at year end rather than a W-2.

Getting this wrong is a compliance problem, not a paperwork preference. The IRS evaluates worker status using common-law rules grouped into behavioral control, financial control and the type of relationship between the parties, not by what a contract calls the worker (IRS Topic no. 762, Independent contractor vs. employee, as of September 2026). If your agency is unsure whether a placement should be W-2 or 1099, that decision belongs with counsel or your accountant before onboarding starts, not with whichever form the worker prefers.

The checklist: before day one, day one, first week

Form I-9: what it requires and the deadline

Form I-9 verifies a worker's identity and authorization to work in the US, and "all U.S. employers must properly complete Form I-9 for every individual they hire for employment," citizens and non-citizens alike (USCIS, Form I-9, as of September 2026). The employee completes Section 1 any time after accepting the job, no later than their first day of employment. The employer completes Section 2 — examining the worker's original documents from the USCIS list — within three business days of the hire date (USCIS I-9 Central, as of September 2026).

Two points staffing agencies get wrong often enough to call out. First, the agency that pays the worker is the employer for I-9 purposes, not the client site the worker reports to, so the I-9 belongs in the agency's file. Second, do not ask for I-9 documents before the offer is made and accepted — see Form I-9 timing in hiring for why that specific sequencing matters and what it can expose the agency to. USCIS also requires employers to retain the I-9 for three years after the date of hire, or one year after employment ends, whichever is later (USCIS, Form I-9, as of September 2026).

What counts as acceptable documentation

The worker chooses which documents to present; the agency cannot demand a specific one. USCIS groups acceptable documents into three lists: List A documents establish both identity and work authorization on their own, such as a US passport or a Permanent Resident Card. List B documents establish identity only, such as a state driver's license, and must be paired with a List C document, which establishes work authorization only, such as an unrestricted Social Security card or a certified birth certificate (USCIS, Form I-9 acceptable documents, as of September 2026). A staffing agency that tells a worker "bring your passport" or "bring your Social Security card and a photo ID" is describing the same two paths, List A alone or List B plus List C, not adding a requirement beyond what USCIS lists.

E-Verify: when it applies to a placement

E-Verify is a free system run by the Department of Homeland Security and the Social Security Administration that compares Form I-9 information against government records (E-Verify, About E-Verify, as of September 2026). It is not required nationwide for private employers. Whether your agency must use it depends on the state you operate in, whether the client's contract requires it of vendors, and whether the agency itself holds a federal contract subject to the E-Verify Federal Acquisition Regulation clause. Check your agency's own obligation on e-verify.gov rather than assuming your last placement's rule still applies to this one, since state requirements and client contract terms both vary.

Where E-Verify does apply, the case has to be created no later than the third business day after the employee starts work for pay, the same clock as I-9 Section 2 (E-Verify FAQ, as of September 2026). If a case is created later than that, E-Verify requires a reason for the delay, so track the deadline the same way you track the I-9 deadline rather than as a separate task on a different schedule.

Timesheets and policies

Paperwork gets a worker legally onboarded; it does not get them paid correctly. Before day one, confirm the worker knows the mechanics of the assignment, not just the compliance forms:

• How to log time — a client kiosk, an agency app, or paper — and by when each day or week.
• Who approves hours, and what to do if that person is out the day timesheets are due.
• Pay schedule and how the worker gets paid: direct deposit, paycard or check.
• Overtime rules, if the assignment is hourly and could run past 40 hours in a week.
• Who to call for a safety issue, a schedule conflict, or a problem at the site, separate from who approves timesheets.

A worker who does not know how to log time correctly in week one often has a wrong first paycheck, and a wrong first paycheck is one of the most common reasons a new temp worker quits an assignment in the first two weeks.

A filled example: one worker's compliance file

An invented placement, showing what should be on file before the worker's first shift:

Mistakes that create liability

None of this replaces legal advice for your agency's specific situation. State laws on background checks, drug testing and worker classification vary and change, and a placement that looks routine can still turn on a detail worth a short call to counsel before day one rather than after a problem shows up.