At some point in the growth of almost every small business, the same question comes up: should we bring HR in-house, or keep outsourcing it through a PEO?
It is the right question to ask. The answer depends on your headcount, your complexity, your growth trajectory, and what you actually need HR to do for your business. This guide lays out the honest comparison so you can make the right call.
What you get with a PEO
A Professional Employer Organization enters into a co-employment arrangement with your business. Your employees remain your employees in every practical sense, but the PEO becomes the employer of record for payroll and benefits purposes.
In exchange for a per-employee fee — typically between $125 and $250 per employee per month — the PEO handles:
- Payroll processing and tax filings
- Benefits administration and access to large-group health insurance rates
- Workers compensation coverage and claims management
- HR compliance across every state where your employees work
- Employee handbook and policy maintenance
- Unemployment claims administration
- Onboarding and offboarding processes
- Access to HR advisors for employee relations issues
Critically, the PEO shares employer liability with you. If an employment-related legal issue arises, the PEO's legal and compliance infrastructure stands between your business and the worst-case outcome.
What you get with in-house HR
An in-house HR function means hiring one or more HR professionals as employees of your business. At the generalist level, you are looking at a salary of $55,000 to $80,000 per year for an HR coordinator or specialist, or $70,000 to $95,000 for an HR manager — plus benefits, payroll taxes, and overhead that add another 25 to 35 percent to the total cost.
In exchange, you get dedicated HR capacity that is fully focused on your business, your culture, and your specific needs. An in-house HR professional can:
- Build and own your culture and employee experience
- Handle complex employee relations issues with deep organizational context
- Design and execute recruiting strategies specific to your hiring needs
- Drive learning and development programs
- Work cross-functionally with leadership on organizational design
What an in-house HR person cannot easily do is replace the infrastructure a PEO provides. Benefits negotiating power, compliance monitoring across multiple states, payroll tax expertise, and workers comp administration all require either additional vendors or significant investment to replicate internally.
The cost comparison
Let's run the numbers at different company sizes.
At 20 employees:
A PEO at $175 per employee per month costs approximately $42,000 per year. A junior HR generalist costs $65,000 in salary plus $16,000 in benefits and taxes — roughly $81,000 total, before the cost of benefits vendors, payroll software, and compliance tools the HR person cannot handle alone.
The PEO is significantly less expensive and delivers more comprehensive infrastructure.
At 50 employees:
A PEO costs approximately $105,000 per year. A mid-level HR manager plus the supporting vendor infrastructure — payroll software, benefits broker, compliance monitoring — runs $130,000 to $150,000. The PEO still has a cost advantage, and it includes co-employment liability protection that in-house HR does not provide.
At 100 employees:
A PEO costs approximately $210,000 per year. At this size, a small in-house HR team (one manager, one coordinator) plus vendors is a realistic comparison, and total cost begins to converge. This is the zone where the decision becomes more nuanced.
At 150 to 200 employees:
At this size, the economics often favor building internal HR capacity. You have enough employees to justify dedicated HR professionals, enough scale to negotiate your own benefits arrangements, and enough complexity to need HR that understands your specific organization deeply.
The compliance argument for a PEO
The cost comparison above understates the PEO's value in one important area: compliance.
An in-house HR professional, no matter how capable, cannot monitor employment law changes across multiple states in real time while also managing recruiting, employee relations, and day-to-day HR operations. The pace of change in 2026 — new paid leave laws, AI hiring regulations, wage transparency requirements, salary threshold updates — requires either a dedicated compliance function or a partner that handles it as part of their core business.
A PEO does the latter. Its compliance team monitors regulatory changes, updates your payroll configurations automatically, revises your policy templates, and proactively notifies you of obligations that apply to your workforce. For a business operating in three or more states, this function alone can justify the PEO relationship.
When in-house HR makes more sense
There are legitimate reasons to build internal HR capacity, even before you hit 150 employees.
**Culture is a competitive differentiator for you.** If attracting and retaining talent is central to your business model — as it is for many technology companies, professional services firms, and consumer brands — you may need dedicated HR that can build culture programs, manage employer branding, and own the employee experience in ways that a PEO relationship cannot support.
**Your HR needs are highly specialized.** Businesses in heavily regulated industries — healthcare, financial services, defense contracting — sometimes need HR professionals with deep domain expertise that a generalist PEO advisor cannot provide.
**You have outgrown the PEO model.** Most PEOs serve businesses up to 500 employees, and some cap at lower thresholds. If you are scaling rapidly and approaching the upper limit of what a PEO serves well, building internal HR infrastructure may need to start now.
A hybrid approach worth considering
Many businesses do not have to choose one or the other. A common and effective structure is to maintain a PEO relationship for payroll, benefits, compliance, and workers comp — the infrastructure layer — while hiring one internal HR professional to own culture, recruiting, and employee relations.
This gives you the best of both: the compliance infrastructure and buying power of a PEO, plus the organizational knowledge and culture-building capacity of a dedicated internal person.
At 30 to 75 employees, this hybrid model often delivers more HR capability per dollar than either option alone.
The bottom line
Below 50 employees, a PEO almost always wins on cost and capability. Between 50 and 150 employees, the right answer depends on your growth rate, industry, and what you need HR to do. Above 150 employees, building internal HR capacity becomes increasingly rational — though many businesses continue with a PEO well past this point because the compliance and benefits value remains significant.
The most important thing is not which model you choose, but whether the HR infrastructure you have in place actually serves your employees and keeps your business compliant.
Explore PEO companies in your state
If you are already using a PEO and questioning whether it is the right one, PEO Alternatives has independent comparisons of the top providers to help you find a better fit.