An onboarding checklist for US new starters
Reviewed by Mellow Editorial Team, HR & payroll content team
Getting a new hire set up correctly in the US requires completing specific legal, tax and payroll steps before or on their first day — not after. Miss one and you risk compliance penalties, delayed pay or a messy audit trail.
Confirm the right to work
Before anything else, verify that your new hire is legally authorized to work in the United States. You must complete Form I-9 — Employment Eligibility Verification — for every employee, regardless of citizenship. The employee fills out Section 1 on or before their first day. You complete Section 2 within three business days of the start date, after physically (or remotely, under authorized procedures) examining acceptable identity and work-authorization documents.
Keep the completed I-9 on file for as long as the person is employed, plus at least three years from the hire date or one year after termination — whichever is later. Do not attach I-9s to the personnel file; store them separately so they are easy to produce if ICE or the Department of Labor requests an audit.
If your state or locality requires E-Verify enrollment, run the new hire through the federal database within three days of their start date.
Collect the tax withholding forms
Hand the employee a Form W-4 (federal) so they can declare their filing status and any adjustments that affect how much federal income tax you withhold. Federal income tax is progressive, running from 10% to 37%, and you calculate withholding from the W-4 instructions and IRS Publication 15-T.
If you operate in a state with its own income tax, issue the state equivalent at the same time. Some states — Texas, Florida and Washington among them — levy no state income tax, so this step does not apply there. Check your specific state's requirements; some also have local income tax forms.
File the completed W-4s and any state forms in the employee's record. You are not required to send them to the IRS unless the agency specifically requests them.
Set up payroll correctly from day one
Add the employee to your payroll system before the first pay period closes. The key figures to configure:
- Social Security: withhold 6.2% of wages from the employee up to the annual wage base, and match that amount as the employer.
- Medicare: withhold 1.45% with no wage cap; match the same as the employer. High earners also trigger an Additional Medicare Tax of 0.9%, which is the employee's obligation — you withhold it once wages exceed the relevant threshold, but you do not match it.
- Federal Unemployment Tax (FUTA) and any applicable state unemployment insurance (SUI) — rates and wage bases vary by state and by your account's experience rating.
Confirm the employee's pay frequency, method (direct deposit requires a bank authorization form) and any voluntary deductions such as health insurance premiums or retirement contributions. If your company offers a 401(k) or similar plan, give the enrollment paperwork on day one — some plans have waiting periods, but starting the clock early matters.
Distribute required notices and policies
Federal and state law requires you to give new hires certain notices at the time of hire. Requirements vary by state, but common items include:
- FLSA wage notice or state equivalent, confirming pay rate, pay day and overtime rules
- Workers' compensation carrier information
- State unemployment insurance notice
- Paid leave notices where state or local law mandates paid sick leave or family leave
- Your employee handbook, with a signed acknowledgment
Employment in the US is generally at-will, meaning either party can end the relationship at any time for any lawful reason. Your offer letter and handbook should reflect this unless you have negotiated a contract with different terms. If you operate in California, be aware that non-compete clauses are prohibited for most employees — include that in your policy review before issuing documents.
Prepare your reporting and record-keeping obligations
Your ongoing compliance calendar starts the moment someone joins. Key obligations:
- Form 941: file quarterly to report federal income tax withheld plus FICA taxes. The first 941 due date after hire depends on when in the calendar quarter the person starts.
- Form W-2: furnish to the employee and file with the Social Security Administration by 31 January of the following year, covering all wages and taxes withheld for the tax year.
- New hire reporting: every state requires employers to report new hires to a state agency, typically within 20 days of the start date. This feeds into the National Directory of New Hires, which is used to enforce child support orders.
Keep payroll records — including time sheets, pay stubs and tax filings — for at least three years under the FLSA. Some states require longer retention. Building that habit from the first hire makes audits and disputes far easier to manage.
If you are hiring across multiple states or need to navigate varying SUI accounts, withholding rules and notice requirements in parallel, a structured payroll process like how Mellow runs payroll across six countries can reduce the coordination overhead considerably.
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