An independent CPA firm would audit a company's financial statements using the financial information in the statements and generally accepted accounting principles as criteria. An IRS auditor would use the tax information filed and tax laws as criteria. An internal auditor would use information from the company's payroll processing system and metrics of efficiency and effectiveness as criteria to evaluate the system. The roles of independent auditors, government auditors, tax agents, and internal auditors all involve evaluation of information against certain criteria but they differ in purpose and oversight responsibilities.