Paychex is a human capital management (HCM) company serving small and mid-sized businesses (SMBs) across the U.S. Paychex helps businesses manage the full employee lifecycle — hiring, onboarding, payroll, benefits, compliance, and retirement — without needing a large internal HR function. As of May 2025, Paychex served approximately 800,000 clients and processes payroll for roughly one in 12 private sector U.S. workers. Paychex operates three platforms: SurePayroll for micro/DIY clients, Paychex Flex for companies up to 99 employees, and Paycor (acquired April 2025) for the 100+ employee segment. Paychex also operates a Professional Employer Organization (PEO), acting as a co-employer and bundling payroll, HR, workers' comp, and health insurance for clients — serving roughly 2.5 million worksite employees. Revenue is primarily driven by subscription and per-employee fees, with a smaller contribution from float income earned on client payroll funds held in transit. Key revenue growth drivers include client count, employee headcount at client businesses, product upsell (expanding from core payroll into PEO, retirement, and insurance), and annual pricing increases. More than half of new payroll clients come through referral channels, particularly CPAs, where Paychex is the preferred provider for the AICPA. Paychex differentiates itself by combining HCM software with hands-on HR advisory and compliance services. The April 2025 Paycor acquisition is the largest deal in Paychex's recent history, adding upmarket client exposure and cross-sell opportunities for PEO and retirement products.