Most small businesses want to offer a 401(k) but never do. The costs, paperwork, and legal liability stop them. A PEO 401(k) plan removes those barriers by pooling your employees into a large, professionally managed retirement plan alongside thousands of workers from other small companies. You get institutional-quality retirement benefits without building or administering a plan yourself.
This guide covers how PEO 401(k) plans work, what they cost, what tax credits you can claim, and what to evaluate before joining one.
Why Most Small Businesses Skip 401(k) Plans
Only 46 percent of employers with fewer than 100 employees offer a 401(k) or similar retirement plan, compared to 89 percent of mid-size firms (BLS, March 2025). The gap is not about willingness. It is about cost, complexity, and risk.
Running a standalone 401(k) requires:
- Choosing a plan provider and negotiating fees
- Filing annual 5500 forms with the Department of Labor
- Running nondiscrimination testing (ADP/ACP tests) every year
- Acting as a plan fiduciary, which carries personal legal liability under ERISA (Employee Retirement Income Security Act)
- Educating employees about investment options and enrollment
For a 20-person company, a standalone plan typically costs $5,000 to $15,000 per year in administration, recordkeeping, and advisory fees before any employer match. The fiduciary liability alone deters many owners. If the plan is mismanaged, the business owner's personal assets are on the line.
The result: employees at small businesses are far less likely to have retirement benefits than employees at larger companies. That makes it harder to recruit and retain good people.
How a PEO 401(k) Plan Works
When you join a PEO (Professional Employer Organization) through a co-employment arrangement, you gain access to the PEO's retirement plan. The PEO sponsors a Multiple Employer Plan (MEP), which is a single 401(k) that covers employees from dozens or hundreds of client companies.
Your employees enroll in the PEO's plan. Contributions are deducted automatically through the PEO's payroll system. The PEO (or its designated plan administrator) handles:
- Plan setup and IRS compliance
- Annual 5500 filing and audit coordination
- Nondiscrimination testing
- Employee enrollment and education
- Contribution processing each payroll
- Loan administration
- Required notices and disclosures
The PEO typically acts as the plan sponsor and takes on significant fiduciary responsibility. This does not eliminate your fiduciary duty entirely (you still have a duty to monitor the plan and ensure it serves your employees' interests), but it transfers the heaviest administrative and compliance burdens off your plate.
What a PEO 401(k) Costs vs. Going Alone
PEO 401(k) plans pool assets from many small employers into a single plan. This creates economies of scale that reduce per-participant costs. However, the fee structure matters.
Most PEO plans charge fees as a percentage of assets under management (typically 0.50 to 1.50 percent of total plan assets annually). Some also charge per-participant fees ($20 to $75 per employee per year). The PEO bundles these costs into your overall PEO service fee, so they may not appear as a separate line item.
The cost advantage is clearest for very small companies (5 to 25 employees). At that size, a standalone plan's fixed costs (audits, TPA fees, recordkeeping minimums) are spread across too few participants to be efficient. A PEO plan absorbs those fixed costs across hundreds of companies.
For larger companies (50+ employees with significant plan assets), the math can flip. Asset-based fees grow with your balance, while a standalone plan's flat fees stay constant. A company with $2 million in plan assets paying 1 percent in a PEO plan spends $20,000 on fees. A standalone plan with flat recordkeeping might cost $8,000 to $12,000.
The key question: are you paying asset-based or flat fees? Ask the PEO for a fee disclosure (they are required to provide one under ERISA) and compare it to standalone quotes.
PEO 401(k) vs. Standalone 401(k)
| Feature | PEO 401(k) Plan | Standalone 401(k) Plan |
|---|---|---|
| Plan sponsor | PEO sponsors a Multiple Employer Plan | Your company is the sole sponsor |
| Setup cost | Included in PEO service (no separate startup fee) | $1,000 to $5,000 in setup fees |
| Annual admin | Bundled into PEO fees (asset-based or per-participant) | $3,000 to $15,000+ depending on plan size |
| Fiduciary burden | PEO assumes plan-level fiduciary duties | You are the primary fiduciary |
| Nondiscrimination testing | PEO handles it | You hire a TPA or do it yourself |
| Investment options | PEO selects the fund lineup | You choose (with advisor help) |
| Payroll integration | Automatic (PEO runs your payroll) | Requires manual integration or third-party connector |
SECURE Act 2.0: Tax Credits That Change the Math
The SECURE Act 2.0 (passed December 2022) created major tax incentives for small businesses offering retirement plans. These credits apply whether you use a PEO plan or a standalone plan, but they make the PEO path even more attractive because your net cost drops significantly.
Startup cost credit. Businesses with 50 or fewer employees can claim 100 percent of plan startup costs as a tax credit, up to $5,000 per year for the first three years. Businesses with 51 to 100 employees get a 50 percent credit on the same costs.
Employer contribution credit. Businesses with 50 or fewer employees can claim a tax credit for employer contributions: 100 percent of contributions in years one and two, 75 percent in year three, 50 percent in year four, and 25 percent in year five. The credit maxes out at $1,000 per eligible employee per year.
Auto-enrollment credit. A $500 annual tax credit for up to three years for plans that include automatic enrollment.
For a 20-employee company making a 3 percent match ($1,200 per employee at $40,000 average salary), the employer contribution credit alone could cover $20,000 or more in the first two years. Combined with the startup credit, many small businesses can offer a 401(k) at near-zero net cost for the first few years.
Note: these credits apply to new plans. If you already had a 401(k) and switch to a PEO plan, you may not qualify. Consult a tax advisor for your specific situation.
What Employees Get
A PEO 401(k) gives your employees access to retirement benefits that look and feel like those at a large corporation:
- Pre-tax or Roth contribution options (or both)
- Employer matching contributions (if you choose to offer a match)
- A diversified investment menu (typically 15 to 30 fund options)
- Online account access and planning tools
- Automatic enrollment (required for new plans starting January 1, 2025 under SECURE Act 2.0, with a default contribution rate of 3 percent that increases 1 percent annually up to 10 to 15 percent)
- Loan provisions (if the plan allows them)
- Hardship withdrawal options
Plans with automatic enrollment see 94 percent participation rates, compared to 64 percent for voluntary enrollment (Vanguard, 2024). If your goal is to help your employees actually save for retirement (not just check a benefits box), auto-enrollment is the single most effective plan design feature.
What to Evaluate Before Joining
Not all PEO 401(k) plans are equal. Ask these questions before signing up:
Fee transparency. Ask for the plan's fee disclosure document (Form 408(b)(2) notice). Look at total plan cost as a percentage of assets, including fund expense ratios, recordkeeping fees, and any revenue sharing. Compare this to standalone quotes from at least two providers.
Investment quality. Review the fund lineup. Are they low-cost index funds, or higher-cost actively managed funds? A plan with average fund expense ratios above 0.75 percent is expensive by current standards. Many standalone plans now offer index funds at 0.03 to 0.10 percent.
Portability. What happens if you leave the PEO? Can employees roll their balances into a new plan or IRA without penalties or blackout periods? Some PEO plans make transitions smooth. Others create complications.
Fiduciary clarity. Get in writing which fiduciary duties the PEO assumes and which remain yours. The DOL (Department of Labor) requires clear documentation of fiduciary responsibility in multi-employer arrangements.
Match flexibility. Can you set your own match formula, or does the PEO dictate terms? Most PEOs allow you to choose your match (including no match at all), but some standardize it across clients.
Bundled requirement. Like most PEO services, you cannot buy the 401(k) alone. It comes with payroll, HR, and benefits. If retirement is your only need, a standalone plan or a Pooled Employer Plan (PEP) through a non-PEO provider may be simpler.
The Bottom Line
A PEO 401(k) gives small businesses an institutional-quality retirement plan without the administrative burden, startup costs, or fiduciary exposure of going it alone. The pooling effect lowers fees for very small companies, and SECURE Act 2.0 tax credits can offset much of the employer's cost in the early years. The trade-off: you accept the PEO's chosen investment lineup and fee structure, and you buy retirement as part of the full PEO package.
For businesses with 5 to 50 employees that want to offer competitive retirement benefits without hiring a benefits consultant, the PEO path is one of the fastest ways to get there. For a broader view of what PEO benefits include beyond retirement, see our guide to how PEO benefits work.
Browse PEO providers in our directory or request a free consultation to compare 401(k) options for your business. Our brokerage team evaluates your needs at no cost to you. PEO providers compensate our brokerage team directly.
Sources
- BLS, "Retirement Benefits: Access, Participation, and Take-Up Rates" (March 2025)
- U.S. Department of Labor, "Understanding Your Fiduciary Responsibilities" (2026)
- U.S. Department of Labor, "A Look at 401(k) Plan Fees" (2025)
- IRS, "401(k) Plan Overview" (2026)
- NAPEO PEO Insider, "The ROI of a Modern 401(k)" (2025)
- NAPEO, "Industry Research & Data" (2025)
