PEO Choices for a Custom Software Shop

Every engineer who touches a client's codebase needs a clean invention-assignment and confidentiality agreement, and that has nothing to do with which PEO you use. A PEO doesn't draft or review those agreements for you. What it does affect is how quickly you can onboard a new hire once your own paperwork is ready, and how cleanly a contractor-to-employee conversion gets handled when a project engineer becomes permanent staff.

Justworks runs a fast, largely self-serve onboarding flow that's easy to pair with your own signed IP documents. TriNet's onboarding is more structured and includes a human HR touchpoint, which some agency owners prefer when a new engineer needs extra explanation of how co-employment and IP obligations interact.

A services shop with lumpy revenue, big project this quarter, a lull the next, needs a PEO relationship that doesn't punish it for hiring in bursts. Justworks' flat per-employee pricing scales cleanly with a growing or shrinking headcount, since you pay for exactly who's on payroll that month.

TriNet's custom pricing can be structured either way depending on your negotiation, but percentage-of-payroll models tend to reward stable, predictable headcount more than the boom-and-bust hiring pattern a lot of dev shops actually run.

It's tempting to keep every engineer on 1099 status to avoid payroll tax and benefits costs, but misclassifying someone who works set hours under your direction, uses your tools, and reports to your project leads is a real risk, not a PEO issue at all, it's an IRS and state labor department issue regardless of which PEO you use.

Where the PEO choice matters is in making the legitimate mixed model easier to run. Justworks includes basic 1099 payment and year-end filing in its core plan. TriNet offers contractor tools too, generally with more formal onboarding, which fits a shop that already has someone dedicated to vendor compliance.

A useful test: if a person on your bench has worked exclusively for you for over a year, follows your sprint schedule, and would need your permission to take on other client work, that's a conversation to have with an employment attorney, not a decision to make based on which PEO offers the smoother contractor portal.

Payroll takes a large bite out of revenue in this sector compared with product or retail businesses, since your team's time is the product¹. That makes the PEO's fee structure worth modeling carefully rather than picking on brand recognition.

• Run your last four quarters of headcount swings against both vendors' pricing models.
• Ask each vendor how contractor-to-employee conversions are handled mid-project.
• Confirm whether either vendor's benefits pool gets better as your headcount grows, or stays flat.
• Check how fast each one can onboard someone when you need them starting Monday, not next month.

If your shop runs ten to thirty engineers with headcount that moves with your pipeline, Justworks' flat pricing and fast onboarding usually wins on both cost and speed. If you're past thirty staff with steadier headcount, competing for senior architects against enterprise employers, and dealing with more complex state tax exposure from a distributed team, TriNet's deeper HR support starts to pay for itself.

Neither one will fix a pipeline problem. A PEO can make payroll and benefits administration close to invisible, but it has no view into whether your last three proposals lost on price or on scope, and it won't tell you when a senior engineer is about to roll off a finishing project with nothing lined up behind it. Keep the PEO decision scoped to what it actually controls, and don't let it eat time you should be spending on the next signed statement of work.