What a PEO Actually Is
A PEO enters a co-employment relationship with your business. Legally, the PEO becomes the "employer of record" for tax and benefits purposes; you retain day-to-day management control. This structure lets the PEO pool your employees with thousands of others to negotiate better benefits rates and spread compliance costs.
The major players: TriNet, Justworks, Insperity, ADP TotalSource, Paychex PEO. Pricing is typically 2–8% of gross payroll or $100–$200 per employee per month, depending on size and services.
The Real Cost Comparison
Take a 30-person company with $2 million in annual gross payroll:
In-house (Gusto + broker-sourced benefits):
- Payroll processing: ~$4,000/year
- Benefits (employer share): ~$240,000/year (at $8,000/employee — small-group rates)
- Workers' comp: ~$30,000/year
- HR/compliance (fractional or software): ~$15,000/year
- Total: ~$289,000/year
PEO (mid-tier provider):
- PEO fee: ~$72,000/year (3.6% of payroll, or ~$200/employee/month)
- Benefits (employer share): ~$195,000/year (at $6,500/employee — large-group PEO rates)
- Workers' comp: included in PEO fee
- HR/compliance: included
- Total: ~$267,000/year
The PEO saves roughly $22,000/year in this scenario — almost entirely from better benefits rates. The PEO's large-group health insurance pricing is the core economic argument, and for companies under 50 employees, it's usually real.
But change the assumptions and the math flips. At 75+ employees, your company can negotiate competitive benefits rates directly, and the PEO fee becomes pure overhead. The breakeven is typically 40–60 employees — below that, PEOs often save money; above that, they usually cost more.
What the Math Misses
Benefits quality. PEO health plans are large-group plans — broader networks, better coverage, lower deductibles than what a 20-person company can buy directly. This isn't just cost; it's a recruiting tool. "We offer Fortune 500 benefits" is a genuine hiring advantage for small firms.
Compliance shield. The PEO handles multi-state registration, tax filings, workers' comp audits, ACA reporting, and employment law compliance. For a company expanding into new states, this alone can justify the fee — a single multi-state compliance failure costs more than a year of PEO fees.
Loss of control. Co-employment means the PEO is involved in terminations, disputes, and policy decisions. Some owners chafe at this. If you have strong internal HR instincts and want full autonomy, the PEO relationship can feel constraining.
The exit problem. Leaving a PEO is disruptive — you're essentially re-establishing your company as an independent employer. New tax IDs, new benefits plans, new workers' comp policy. It's doable, but it's a project. Some companies stay with PEOs longer than optimal because switching feels daunting.
Service quality variance. PEO service ranges from excellent to maddening. The industry has a reputation problem — aggressive sales, inconsistent support, surprise fees. Due diligence on the specific PEO (not just the model) is essential. Talk to current clients, not just references the PEO provides.
The Decision Framework
Choose a PEO when:
- You're under 40 employees and growing
- Benefits costs are a pain point in recruiting
- You're expanding to multiple states
- You have no internal HR expertise and don't want to build it
- Compliance risk keeps you up at night
Stay in-house when:
- You're over 60 employees (the economics flip)
- You have competent internal HR or a strong fractional HR partner
- Benefits are already competitive (or you're in a low-cost benefits market)
- You value full control over employment decisions
- Your workforce is concentrated in one state with straightforward compliance
"A PEO doesn't reduce your HR costs. It converts unpredictable HR risks into a predictable monthly fee — and for many growing companies, that predictability is worth more than the savings."
The Bottom Line
The PEO decision isn't really about payroll — it's about whether you want to be in the benefits and compliance business. For most companies under 50 employees, the answer is no, and a good PEO is the rational choice. Above that threshold, the math usually favors building internal capability. Know where you sit on that curve, and decide accordingly.
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