Co-Employment

Practical implication: co-employment via PEO is generally lower-risk because it is a designed arrangement with explicit liability allocation.

Co-Employment is a contractual arrangement where a client business and a PEO or staffing agency share employer responsibilities, with the PEO handling payroll, benefits, and compliance while the client retains day-to-day work direction.

Co-employment vs joint employment: the critical distinction

These terms are routinely conflated, but the legal and operational implications differ materially.

Practical implication: co-employment via PEO is generally lower-risk because it is a designed arrangement with explicit liability allocation. Joint employment is the higher-risk pattern, typically unintentional and often discovered after a wage-hour claim, NLRB charge, or discrimination complaint.

The professional employer organization (PEO) model

In a PEO arrangement, the PEO and client enter into a Client Service Agreement that allocates employer responsibilities:

• PEO responsibilities. Payroll processing and tax remittance, benefits administration (often providing access to better health plans through large-group purchasing), workers’ compensation, unemployment insurance, HR compliance support, employee onboarding.
• Client responsibilities. Day-to-day direction of work, hiring and firing decisions, business operations, customer relationships.
• Worker’s perspective. Receives paycheck from PEO; W-2 issued by PEO; reports to client manager; works at client’s location.

CPEO designation matters: the IRS Certified Professional Employer Organization (CPEO) program, established under the Small Business Efficiency Act of 2014, designates PEOs meeting specific financial, bonding, audit, and operational standards. CPEOs take sole liability for federal employment taxes. Non-certified PEOs do not provide this protection, if the PEO fails to remit payroll taxes, the client remains liable under the trust-fund recovery doctrine.

PEO vs staffing agency: different arrangements, different liabilities

Practical guidance: PEO suits small and mid-size businesses wanting full HR support. Staffing agency suits temporary capacity needs. When ‘temporary’ assignments stretch beyond 6 months and the worker integrates into client operations, joint employer risk rises sharply.

The FLSA and NLRB joint employer tests

FLSA joint employment

Under the Fair Labor Standards Act, joint employment exists where two or more employers share control over the essential terms and conditions of employment. Joint employers are jointly and severally liable for wage and hour violations. The applicable rule has shifted across administrations:

• 2020 Trump-era rule. Narrow four-factor test focused on direct control. Rescinded.
• 2024 Biden-era rule. Broader test considering both direct and indirect control. Subject to ongoing legal challenge.
• Current posture. Practitioner approach: assume broader interpretation; structure relationships to minimise shared control over essential terms.

NLRB joint employment

The NLRB’s 2023 rule considers joint employer status based on the ability to control essential terms, even when that control is exercised indirectly or reserved but not exercised. Both employers can be held to bargain with the same union and be responsible for unfair labor practices.

The vizcaino v. microsoft case: the cautionary precedent

Vizcaino v. Microsoft Corp. (9th Cir. 1996, 1997, 1999) is the most-cited co-employment / contingent-worker misclassification case. Microsoft engaged thousands of workers as ‘temporary’ through agencies for periods ranging from months to many years, excluding them from Microsoft’s employee benefits including the employee stock purchase plan and 401(k). The Ninth Circuit held that these workers were ‘common law employees’ of Microsoft despite the agency-employer paperwork, and were entitled to participate in Microsoft’s benefit plans. The case settled in 2000 for approximately $97 million.

Lessons: long-term ‘temporary’ workers integrated into operations risk being deemed common-law employees regardless of who pays them; benefit plan exclusions based on ‘agency’ status are not protected by contract language alone; multi-year contractor arrangements producing material benefits exclusion are particularly exposed.

Risk mitigation: 8-point playbook

1. Be deliberate about which model you’re using. PEO co-employment vs staffing agency vs direct hire are different arrangements with different risks.

1. Use Certified PEOs (CPEOs) where possible. IRS CPEO status provides statutory protection on employment taxes. Verify CPEO status before signing.
2. Document the Client Service Agreement carefully. Allocate responsibilities explicitly: who handles which HR function, indemnity terms, escalation paths.
3. Set staffing engagement time limits. Track agency-worker tenure; convert to direct hire or end engagement before joint employer / common-law employee risk crystallises (typically 6-12 months).
4. Don’t extend benefits to staffing workers. Granting employee benefits to agency workers is the most-litigated factor in misclassification cases (Vizcaino).
5. Maintain documentation of decision-making. Who makes hiring decisions, supervises, determines pay rates, handles discipline. Control facts determine the joint employer outcome.
6. Audit your staffing relationships annually. Tenure, integration patterns, control facts. Identify high-risk arrangements before plaintiffs do.
7. Engage employment counsel before scaling. Co-employment and joint employer issues are state- and circuit-specific. Multi-state employers especially need counsel.

See also Blended Workforce for workforce composition context, Contingency Recruitment for staffing agency context, At-Will Employment for the US employment baseline, and Back Pay for wage liability context.

Frequently asked questions