People’s mental representation of expenditures is crucial to their budgeting. This article proposes that much like how they represent natural kinds (e.g., animals and plants), people represent expenditures in a hierarchical taxonomy. Seven studies, supported by six norming studies and three pilots, revealed that expenditures are represented hierarchically. We first recover people’s mental representations using a successive pile-sort method that asks people to form hierarchies of categories with common expenditures (e.g., rent, dining out, etc.). The pile-sort reveals consensus in people’s representations of expenditures and that these representations are relatively stable over time. Further, people’s adjustment in their spending behavior can be predicted by the distance between items in their representation. Specifically, when people overspent on an item, they spontaneously adjust spending more on taxonomically closer items. We examine this spontaneous adjustment behavior using both laboratory studies and field data with 6.5 million grocery shopping trips over 12 years. The findings highlight the connection between mental representation and consumer behavior, and they emphasize the importance of studying concepts and categories in the context of consumption.