Human Resource Laws and Regulations: The Complete US Guide by Company Size

Federal employment law does not apply uniformly to every business. Which laws apply to you depends primarily on one number: how many employees you have. A company with 10 employees faces a different set of legal obligations than a company with 50, and both face different requirements than a company with 100. The problem is that no single government resource lays this out clearly. The Department of Labor lists laws alphabetically. The EEOC explains what it enforces but not what other agencies enforce. State agencies cover state law but not federal.

This guide organizes every major US human resource law by the employee threshold at which it applies, so you can look at your headcount and know exactly which laws govern your business. It covers the 18 federal laws that matter most, the record retention requirements that come with them, the 2026 regulatory changes you need to track, and how federal and state laws interact when they conflict. Research shows that only 12% of employees strongly agree their company does onboarding well (Gallup), and compliance failures during onboarding are a major contributor. The HR rules and regulations guide covers the practical compliance steps in more detail.

HR Laws at a Glance: Which Laws Apply to Your Business

This matrix is the reference you will come back to. It lists every major federal employment law, the employee count at which it takes effect, and the core compliance requirement. The thresholds are cumulative: a business with 50 employees must comply with every law at the 1+, 15+, 20+, and 50+ levels.

Two important notes. First, employee counts for most federal laws include all employees on payroll, not just full-time. Part-time employees count toward the threshold in most cases. Second, these are federal minimums. Many states apply anti-discrimination protections starting at 1 employee, require paid family leave regardless of company size, or mandate benefits that federal law does not require. Always check your state's requirements in addition to the matrix above. The compliance hub has state-by-state guides for all 50 states.

Anti-Discrimination Laws

Anti-discrimination laws form the largest category of federal employment regulation. They prohibit employment decisions based on protected characteristics and require employers to provide reasonable accommodations in certain circumstances.

Title VII of the Civil Rights Act (15+ employees)

Title VII prohibits discrimination based on race, color, religion, sex (including pregnancy, sexual orientation, and gender identity), and national origin. It covers every aspect of employment: hiring, firing, pay, promotions, training, and working conditions. It also prohibits retaliation against employees who file discrimination complaints or participate in investigations. Compliance requires posting EEO notices, maintaining hiring records for 1 year, and having a process for handling discrimination complaints.

Americans with Disabilities Act (15+ employees)

The ADA prohibits discrimination against qualified individuals with disabilities and requires employers to provide reasonable accommodations unless doing so would cause undue hardship. A reasonable accommodation is any modification to the job, workplace, or work process that enables a qualified person with a disability to perform essential functions. Examples include modified schedules, ergonomic equipment, and restructured job duties. The interactive process (a conversation between employer and employee about possible accommodations) is required whenever an employee requests accommodation.

Age Discrimination in Employment Act (20+ employees)

ADEA protects workers aged 40 and older from discrimination in hiring, firing, compensation, and terms of employment. It applies at the 20-employee threshold, which is different from the 15-employee threshold for Title VII and ADA. Mandatory retirement policies are prohibited for most positions.

Pregnant Workers Fairness Act (15+ employees)

The PWFA, effective since June 2023, requires employers to provide reasonable accommodations for known limitations related to pregnancy, childbirth, or related medical conditions. This is broader than the original Pregnancy Discrimination Act because it creates an affirmative right to accommodation, not just protection from discrimination. The new hire paperwork guide covers how to handle pregnancy-related documentation during onboarding.

Wage, Hour, and Classification Laws

The Fair Labor Standards Act is the foundational wage and hour law. It applies from your first employee and governs minimum wage ($7.25 federal, though most states set higher rates), overtime pay (1.5x regular rate for hours over 40 per workweek for non-exempt employees), child labor restrictions, and recordkeeping requirements.

The most consequential FLSA compliance issue for small businesses is employee classification: correctly identifying each worker as exempt or non-exempt from overtime requirements. Misclassification exposes the business to back pay claims for all unpaid overtime, liquidated damages equal to the back pay amount, and potential penalties. The classification test examines job duties and salary level, not job title. Calling someone a "manager" does not make them exempt if their actual work does not meet the duties test.

The Equal Pay Act, which applies from employee one, requires equal pay for equal work regardless of sex. "Equal work" means jobs that require substantially equal skill, effort, and responsibility performed under similar working conditions. Pay differences are permitted when based on seniority, merit, quantity or quality of production, or any factor other than sex. The employee vs contractor guide covers the separate but related question of worker classification under IRS and DOL standards.

Leave Laws

The Family and Medical Leave Act requires employers with 50 or more employees to provide up to 12 weeks of unpaid, job-protected leave per year for qualifying reasons: birth or placement of a child, serious health condition of the employee or an immediate family member, or qualifying exigencies related to military service. Employees are eligible after 12 months of employment and 1,250 hours worked.

FMLA is the federal floor. Many states have enacted their own paid family and medical leave (PFML) programs that provide paid leave, apply to smaller employers, and cover additional situations. As of 2026, 13 states plus DC have mandatory PFML programs. If your business operates in multiple states, you may face different leave requirements in each one. The HR functions guide covers how leave management fits into the broader set of HR responsibilities.

USERRA (Uniformed Services Employment and Reemployment Rights Act) applies from employee one and requires employers to reemploy service members returning from military duty in the same position they would have held had they not been absent, with the same seniority, status, and pay. There is no minimum company size for USERRA.

Workplace Safety (OSHA)

The Occupational Safety and Health Act applies to virtually all private employers regardless of size. The General Duty Clause requires every employer to provide a workplace "free from recognized hazards that are causing or are likely to cause death or serious physical harm." Beyond the general duty, specific OSHA standards apply depending on your industry.

Small business compliance essentials: display the OSHA "Job Safety and Health" poster, maintain injury and illness records on OSHA Form 300 (employers with 10 or fewer employees in certain industries are partially exempt from recordkeeping), report workplace fatalities within 8 hours and hospitalizations within 24 hours, and provide required safety training for your industry. OSHA penalties for serious violations can reach $16,131 per violation, with willful violations up to $161,323 (Department of Labor).

Record retention for OSHA is among the longest of any federal requirement: injury and illness logs must be kept for 5 years, and exposure/medical records for the duration of employment plus 30 years. The record retention guide covers the full schedule.

Hiring and Immigration Laws

Every employer must verify employment eligibility using Form I-9 for every person hired, including US citizens. The form must be completed by the end of the employee's third business day. I-9 violations carry fines ranging from $252 to $2,507 per form for first offenses, escalating to $2,507 to $25,076 for repeat violations. I-9 forms must be retained for 3 years from the date of hire or 1 year after termination, whichever is later.

The Fair Credit Reporting Act (FCRA) governs background checks. Before running a background check, employers must provide a standalone written disclosure and obtain the candidate's written authorization. If the background check leads to an adverse employment decision, the employer must follow a two-step process: send a pre-adverse action notice with a copy of the report, wait a reasonable period, and then send a final adverse action notice.

Ban-the-box laws, which restrict when employers can ask about criminal history, now exist in over 35 states and 150 local jurisdictions. Some apply only to public employers while others cover private employers at various size thresholds. The onboarding checklist includes the I-9 and background check steps in the correct sequence.

Benefits Compliance

COBRA requires employers with 20 or more employees to offer continuing health coverage to employees and dependents who lose coverage due to a qualifying event (termination, reduction in hours, divorce, death). Coverage must be offered for 18 to 36 months depending on the qualifying event. The employee pays the full premium plus a 2% administrative fee.

The Affordable Care Act employer mandate applies at 50 full-time equivalent employees. Applicable large employers must offer affordable minimum essential coverage to full-time employees or pay a penalty. For businesses under 50 employees, the ACA employer mandate does not apply, but you may still be eligible for QSEHRA (Qualified Small Employer Health Reimbursement Arrangement) to help employees with health costs. The QSEHRA guide covers eligibility and setup.

ERISA governs employer-sponsored retirement and health plans. If you offer a 401(k), health plan, or other benefit plan, ERISA requires plan documentation, fiduciary responsibility, reporting and disclosure to participants, and a claims and appeals process. Records must be kept for 6 years.

Other Federal Laws You Should Know

The NLRA deserves special attention because it applies from your first employee and is often misunderstood. Section 7 protects employees' right to discuss wages and working conditions with each other. Policies that prohibit employees from discussing their pay are illegal under the NLRA, even at a company with 5 employees. The company policy guide covers how to write policies that comply with NLRA requirements.

2026 Regulatory Updates Employers Need to Track

Employment law changes constantly, especially at the state level. These are the developments that most directly affect businesses with 5 to 100 employees.

The most actionable recommendation: review your state's employment law changes at the start of each year. State legislatures typically enact employment laws that take effect January 1 or July 1. The HR trends guide covers the broader regulatory landscape, and the EEO reporting guide covers the filing process for companies approaching the 100-employee threshold.

Federal vs State: How They Interact

The general rule is simple: when federal and state laws conflict, the law that provides greater protection to the employee applies. In practice, this means state law usually wins because states tend to set higher minimums and broader protections than federal law.

For businesses with employees in a single state, the compliance path is straightforward: apply the higher standard between federal and state law for each requirement. For multi-state employers, each state's laws apply to employees working in that state. A clear employee handbook that references applicable state-specific policies is the simplest way to document compliance across states.

Record Retention Schedule

Different laws require different retention periods. Missing records during an audit or investigation creates a presumption against the employer, meaning the agency assumes the worst when documentation is absent.

The practical rule for businesses without a dedicated HR department: retain all employee records for at least 7 years after termination. This single policy covers nearly all federal requirements and most state requirements. Digitizing records through a document management system eliminates the storage problem and makes retrieval during audits straightforward. The employee file organization guide covers the three-file system and digital storage setup. For I-9 specifics, the personnel file guide explains what goes in each file category.

HR Compliance Checklist

If you do not have a dedicated HR person, this checklist covers the compliance fundamentals that apply to most businesses. Check the items that apply at your employee count using the threshold matrix above.

A platform like FirstHR automates the document collection, e-signature, and retention pieces of this checklist. I-9s, W-4s, handbook acknowledgments, and training completions are tracked automatically, with compliance deadlines flagged before they pass. For the full onboarding compliance workflow, the compliance onboarding guide covers every step from offer acceptance through Day 90. The HR processes guide covers how these compliance requirements fit into your broader HR workflows.

Frequently Asked Questions