While there isn’t one standard classification system, PEOs differ in several important ways:

By certification status:

  • Certified PEOs (CPEOs) have earned IRS certification by meeting specific financial and operational standards
  • Non-certified PEOs provide similar services but haven’t pursued CPEO status

By service approach:

  • Full-service PEOs offer comprehensive HR outsourcing including payroll, benefits, compliance, and risk management
  • Administrative Service Organizations (ASOs) provide similar services without the co-employment relationship

By client size:

  • Small business PEOs specialize in companies with 5-50 employees
  • Mid-market PEOs focus on businesses with 50-500 employees
  • Enterprise PEOs serve organizations with 500+ employees