Abstract: Categorization of data may be performed using rule-based data categorization. Rules may be used to categorize the data into a limited number of categories for a temporary, ad hoc, or updatable process. The rules may be validated to make sure the rules are not ambiguous, contradictory, unattainable, or otherwise ineffective. The rules may include a priority value which may be used as a tie breaker when more than one rule applies to a record. To implement the rules, a lookup flow may be generated to enable rapid or quick traversal of applicable rules for a particular lookup while bypassing at least a portion of the rules. In some embodiments, a record (e.g., an item, etc.) may be categorized during a transaction process to determine a tax classification, a promotion, or another type of classification, which may then be used to complete the transaction.