Abstract: According to the present invention, a system and method for checking expense entries for compliance with policy rules and detecting the possibility of fraud is provided. The preferred embodiment includes a policy checker comprising a knowledge based system designed to determine expense entries' compliance with policy rules and detect a possibility of fraud. The preferred embodiment also includes an auditor workflow system that works with the policy checker to guide manual audits of those expense entries that are not in compliance with the policy rules. The preferred embodiment also includes a data pattern analyzer that detects patterns of behavior that can be indicative of fraud. The preferred embodiment also includes a prioritizer for ranking detected policy violations. These systems work together to provide an automated system for checking expense entries for compliance with company rules, detecting instances where fraud is likely, and generating the appropriate reports.