Preparing for an HR or payroll audit in the United States
Reviewed by Mellow Editorial Team, HR & payroll content team
An HR or payroll audit — whether internal or triggered by a government agency — is manageable if your records are in order before it starts. The core obligation is simple: demonstrate that you paid people correctly, withheld the right taxes, and followed applicable employment law. Everything else flows from that.
Understand what auditors actually look at
Auditors from the IRS, Department of Labor (DOL), or a state agency are not looking for technicalities. They are checking whether your records match your payments and your filings.
The IRS focuses on worker classification, payroll tax deposits, and whether your Forms W-2 and 941 reconcile. The DOL focuses on wage and hour compliance under the Fair Labor Standards Act (FLSA): minimum wage, overtime pay, and recordkeeping. State agencies add their own layer — state income tax withholding, state unemployment insurance (SUI), and any state-specific leave or wage laws.
An internal HR audit covers more ground: hiring documentation, I-9 compliance, benefits enrollment records, and policy consistency.
Get your payroll tax records straight
Start with the paper trail that federal agencies expect to find.
Form W-2. You must furnish W-2s to employees and file them with the Social Security Administration by January 31 each year. For the 2025/26 tax year, confirm those filings went out on time and that the figures are accurate.
Form 941. This quarterly return reports wages paid, federal income tax withheld, and FICA taxes. FICA consists of Social Security at 6.2% (employee side, up to the annual wage base) plus Medicare at 1.45% with no cap. Employers match both. There is also a 0.9% Additional Medicare Tax on high earners, though that is withheld only from the employee. Pull every 941 filed in the past three to four years and verify that the totals reconcile with your payroll register.
Federal income tax withholding. Verify that each employee has a current Form W-4 on file and that your payroll system applied the correct withholding using that form. Federal income tax is withheld using the progressive bracket structure (10% through 37%).
1099-NEC. If you paid any independent contractor $600 or more in a calendar year, a 1099-NEC was due by January 31. Missing 1099s are a common audit trigger, especially when the IRS cross-references contractor income.
Review worker classification carefully
Misclassifying employees as independent contractors is one of the most consequential errors an audit can expose. If a worker you treated as a contractor is reclassified as an employee, you face back payroll taxes, interest, and penalties — covering both the employer and employee share of FICA for every year in question.
The IRS uses a behavioral control, financial control, and type-of-relationship test. The DOL applies an economic reality test under the FLSA. These tests differ, and a worker can be an employee under one and a contractor under another. If any classification is borderline, document your reasoning now — before an auditor asks.
Audit your wage and hour records
The FLSA requires you to keep payroll records for at least three years and time-and-attendance records for at least two years. In practice, keeping everything for at least four years is safer.
Check that:
- Non-exempt employees were paid at least the applicable minimum wage (federal or state, whichever is higher) for all hours worked.
- Overtime was paid at 1.5 times the regular rate for hours over 40 in a workweek.
- "Off-the-clock" work was not excluded from time records — a common source of DOL complaints.
- Exempt employees actually meet the salary basis and duties tests for their classification.
Employment in the US is generally at-will, but that does not affect wage and hour obligations. Employees can still file FLSA complaints regardless of how or why the employment relationship ended.
Check your HR documentation
Beyond payroll, an HR audit covers the records that support compliance with federal and state employment law.
I-9 forms. Every employee hired after November 6, 1986 must have a completed I-9 on file. Retain I-9s for three years from the hire date or one year after termination, whichever is later. Keep them separate from personnel files.
State-specific rules. Several states layer additional obligations on top of federal requirements. California, for example, prohibits most non-compete clauses — having unenforceable non-competes in your offer letters or employment agreements is an audit risk and a legal one. States without income tax (such as Texas, Florida, and Washington) still have unemployment insurance and state-specific wage laws.
Leave records. There is no federal statutory paid annual leave or paid sick leave, but many states and municipalities have their own requirements. Document which leave policies apply to which employees and verify that actual leave taken was recorded and paid correctly where required.
Offer letters, job descriptions, and policy acknowledgments. These show that employees were informed of their terms of employment and that policies were applied consistently. Inconsistency — where one employee was disciplined under a policy another was not — is exactly what an employment lawyer or state agency will look for in a discrimination or wrongful termination claim.
If you rely on a payroll provider or PEO, confirm that you can access and export all underlying records. How Mellow runs payroll across six countries on one platform illustrates why portability and auditability of records matter regardless of the tool you use.
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