You’re trying to close an add-on fast, but you can’t afford a people surprise that forces a purchase price adjustment, derails integration, or triggers a compliance mess. The point of an HR due diligence checklist isn’t to collect “everything HR has.” It’s to surface liabilities, costs, and operational constraints early enough to price them, paper them, and plan around them.
Below is a practical checklist, organized the way we see private equity teams and portfolio operators actually use it: confirm the legal/employment perimeter, quantify workforce cost and risk, and understand what will break on Day 1 if you don’t plan.
Start by defining what you’re buying: entities, locations, and who employs whom
Add-on deals get messy when the workforce doesn’t sit neatly in the entity you think you’re acquiring. Before you chase policies and benefits, lock down the basics.
You’ll want current company contact information and a clear list of legal entities, DBAs, and associated EINs—and specifically which entities employ the people in scope. This sounds administrative, but it drives everything that follows: payroll tax filings, benefits plan sponsorship, workers’ comp policies, and who has authority to sign employment documents.
Then map operating locations. Get addresses, business activities, and headcount by site, and identify remote employees by state or country. Remote dispersion changes your compliance footprint and may introduce registration, tax withholding, leave, and wage/hour requirements that won’t show up if you only look at headquarters.
If the target is a federal contractor under OFCCP definitions, confirm whether an Affirmative Action Plan exists and which establishments are covered. That single fact can change the compliance workstream and the integration approach.
What to check internally as the buyer: whether your integration model assumes a clean employing-entity structure. If not, decide early whether you’ll re-paper employment, merge entities, or carry complexity for a period.
People data that actually changes value: census, org design, and contingent labor
PE buyers often get an “employee list.” That’s not enough. Ask for an employee census that ties together job and reporting data with comp, classification, and demographic/immigration fields. At minimum, you’re looking to validate wages/salaries, bonus targets, FLSA status, hire/rehire dates, and supervisor relationships. You’re also looking for potential red flags: inconsistent classifications, missing fields, or data that suggests informal practices.
Pair the census with a current organizational chart that includes open positions, contractors, and contingent labor. The vacancies matter. A critical role that’s been open for months can be an execution risk right when you’re counting on synergy capture.
Contingent labor deserves its own spotlight. Get a schedule of consultants, contractors, and contingent workers, with scope of work, dates, rates, and any staffing agency relationships. In add-ons, a surprising amount of “core work” can sit outside the employee base. That affects costs, IP protection, co-employment exposure, and integration planning.
Also confirm whether the company sponsors immigration and what the commitments look like: visa types, expirations, pending applications, and the company’s policy on covering costs. Even if it’s a small population, it’s a continuity risk if you don’t plan for sponsorship responsibility post-close.
Compensation, benefits, and trailing liabilities: find the costs that don’t show up in EBITDA
This is where HR diligence earns its keep in a buy-and-build. You’re trying to quantify obligations and understand which programs will create retention risk or immediate cash needs.
On compensation, focus on incentive plans and transaction-related obligations. Collect documentation and schedules for short-term and long-term incentive plans, sales commission plans, performance bonus plans, and any retention bonus arrangements or retention letters. Pay special attention to change-of-control obligations. You need a schedule of who’s covered, what triggers payment, and estimated costs under the proposed transaction.
Don’t ignore severance arrangements. Request severance plan documents and any employee-specific agreements, plus copies of severance awards where they exist. If the target has promised benefits continuation or special terms to specific people, that’s a real liability—especially if you plan to restructure.
On health and welfare benefits, establish whether coverages are self-insured or fully insured. That determines whether you’re dealing with incurred-but-not-paid claim exposure and whether an escrow may be appropriate for trailing claims in a self-insured arrangement. Ask for plan costs and employee contributions by coverage tier, current invoices (or rates and renewals if invoices aren’t separated by the unit in scope), and a benefits census showing elections.
Then assess administration maturity: how enrollment changes flow into HRIS/payroll, how carrier invoices are reconciled, and whether nondiscrimination testing has been completed where applicable. These aren’t “back office” details. Weak controls create billing errors, employee relations issues, and compliance exposure right after close.
Compliance and employee relations: identify lawsuits, unions, and practices you’ll inherit
Fast add-ons can tempt teams to treat compliance as a post-close fix. That’s a mistake. Some risks don’t wait.
Request OSHA logs and required workforce regulatory reporting where applicable, such as EEO-1 and VETS reporting for prior years. Review workers’ compensation policies and a three-year claims history, including open claims and reserves. If the company has specific COVID-related workplace policies (or legacy practices that persist), capture what they are and whether there are outstanding issues.
Employee and contractor complaints and investigations over the last three years are another key input. You’re not trying to relitigate them. You’re trying to understand pattern risk, management behavior, and whether there are unresolved issues that could escalate post-close. Similarly, get a schedule of employee-related litigation and any EEOC charges served on the company, with status and obligations. Handle these materials carefully and with counsel involvement where privilege applies.
If there’s any labor union presence or activity, pull collective bargaining agreements, note expiration dates, and understand any grievances, arbitrations, disputes, or organizing activity. Even in non-union environments, an acquisition can trigger workforce anxiety. You don’t want to learn about a brewing campaign after you announce the deal.
Finally, confirm baseline employment practices: handbook, key policies, holiday schedule, PTO rules and balances, and payroll practices including pay frequency, premiums (shift differential, on-call, overtime rules), and wage deduction/clawback practices. These are common sources of post-close employee friction and wage/hour exposure—especially when you’re trying to standardize across a platform.
A practical next step: run a “Day 1 readiness” review on the checklist
If you’re actively doing add-ons, don’t treat this as a one-time request list. Use it as a repeatable filter.
Take the categories above and run a quick Day 1 readiness review before signing: confirm employing entities and states worked, validate census quality, quantify incentive and change-of-control exposure, and pressure-test benefits and payroll administration controls. If you can’t get clean answers, that’s not a reason to walk away automatically—but it is a reason to price risk, add deal protections, and build an integration plan that assumes extra lift in HR, payroll, and compliance.
Why 29Bison?
People decisions can change the outcome of a deal. 29Bison helps private equity firms and business leaders assess workforce risks before close, plan HR integration after an acquisition, and evaluate leadership and culture. Our Fractional HR Operating Partner service provides HR leadership across portfolio companies.
If you're preparing for a transaction or deciding what your HR team needs next, talk with 29Bison about the people questions you need to answer.