PEO for Union Employers: CBA Compliance, Multi-Employer Plans, and Liability

Standard PEO infrastructure assumes a non-union workforce. The benefits structure runs through the PEO master plan; workers' comp comes through the PEO pool; payroll runs on the PEO's standard cadence and deduction logic. Union operations break those assumptions.

Union employees often participate in multi-employer pension plans (MEPPs) through their collective bargaining unit. The PEO must accurately calculate, withhold, and remit contributions to MEPPs — and report them according to plan rules. Standard PEOs don't support MEPP contribution administration; specialized PEOs do.

Union workers may have vacation, holiday, and apprenticeship funds administered through the union, separate from the PEO. Contributions go to the fund, not retained as accrued PTO on the PEO's books. Most PEO HRIS platforms don't natively handle this; PEOs with union experience have built workarounds.

Grievance procedures sit at the co-employment liability boundary. When a grievance involves PEO-handled functions (payroll error, benefits eligibility, ACA reporting), the PEO must participate in the grievance response — but liability for the underlying issue depends on the CSA.

The collective bargaining agreement is the controlling document for most union workforce decisions. Under co-employment, the PEO must operate within the CBA's constraints for:

• Wage rates and scheduled increases — Payroll must reflect CBA-mandated rates and step increases. PEO HRIS must handle multi-rate scenarios (apprentice rates, journeyman rates, shift differentials).
• Benefits structure — CBA may specify health plan tier, prescription coverage levels, or vision/dental benefits that diverge from the PEO master plan. Either the client carves out benefits (loses master-plan economics) or finds a PEO that can match CBA-specified benefits.
• Hours and overtime — CBA may specify overtime triggers that differ from FLSA (daily overtime, weekly thresholds, double-time on holidays). PEO payroll must enforce CBA rules.
• Grievance and arbitration procedures — Specified timelines and steps. PEO must support compliance.
• Union dues and assessments — Calculation and remittance to the union, typically with reporting requirements.

MEPPs are the most operationally complex piece. Each contributing employer must:

• Calculate contributions per CBA formula (often $/hour worked or % of gross wages)
• Report contribution amounts to the fund with required detail (hours, eligible wages, employee identifiers)
• Remit funds on the schedule specified by the plan (typically monthly)
• Submit annual contribution reconciliation
• Handle pension protection act compliance and zone-status implications (endangered/critical/critical-and-declining plans have different employer obligations)

PEOs that don't support MEPP administration either decline union accounts or require the client to handle pension administration outside the PEO — which loses much of the PEO economic case.

Based on our placement experience, the PEOs that consistently deliver for union employers:

• ADP TotalSource: Largest union-employer PEO book by client count. Built infrastructure for MEPP administration, CBA-compliant payroll, and grievance support.
• Insperity: Strong union-employer practice with construction-trade focus (electrical, plumbing, sheet metal). Active relationships with major trade-union benefit funds.
• CoAdvantage: Specialized union shop in construction. Less national scale but deep CBA compliance for clients in their footprint.
• Paychex Employer Services: Mid-market construction union employers. Solid MEPP administration; less benefits depth.

For each, request references from union-employer clients specifically. The "we can do unions" assertion in a sales pitch is meaningless without operational proof.