Paychex provides payroll processing, human resources services and benefits administration primarily to small and medium-sized businesses, competing most directly with ADP in the outsourced payroll industry. Payroll is a mission-critical, recurring task that businesses rarely switch providers for once established, since moving payroll systems carries real operational risk, giving Paychex an unusually sticky, subscription-like revenue base. The company's focus on smaller businesses, often with simpler payroll and HR needs than large enterprises, differentiates its customer base somewhat from competitors more focused on large corporate clients. Paychex also earns meaningful interest income on client funds it temporarily holds between collecting payroll taxes and remitting them to government agencies, giving its earnings a modest sensitivity to prevailing interest rates.