Fair Labor Standards Act (FLSA): Federal law governing minimum wage, overtime pay, recordkeeping, and child labor standards. Key considerations include minimum wage requirements, overtime calculations, and employee record maintenance.

Internal Revenue Code: Federal tax regulations including requirements for federal tax withholding, Social Security and Medicare (FICA) contributions, and Federal unemployment tax (FUTA) compliance.

Employee Retirement Income Security Act (ERISA): Federal law governing employee benefits and retirement plans, including requirements for handling retirement plan contributions and benefits administration.

Data Privacy and Security Laws: Various federal and state laws including Gramm-Leach-Bliley Act, state-specific data protection requirements, and GDPR considerations for EU employee data.

Family and Medical Leave Act (FMLA): Federal law requiring covered employers to provide employees with job-protected leave for qualified medical and family reasons, including leave tracking and administration requirements.

State Tax Laws: State-specific requirements for income tax withholding, unemployment insurance, and workers' compensation compliance varying by jurisdiction.

State Wage and Hour Laws: State-specific regulations governing minimum wage, overtime, pay frequency, and final paycheck requirements that may exceed federal standards.

SOC Compliance Standards: Service Organization Control (SOC) 1 and SOC 2 compliance requirements for service organizations handling financial information and sensitive data.

ISO 27001: International standard for information security management systems, crucial for protecting sensitive payroll and employee data.

PCI DSS: Payment Card Industry Data Security Standard requirements if handling payment card data in payroll processing.

Industry-Specific Regulations: Specialized requirements for different sectors including HIPAA for healthcare, financial services regulations, and government contractor requirements.