1. A method of automatically splitting a financial transaction into multiple categories, the method comprising: maintaining a record of multiple transactions conducted with a first payee by one or more users including a first user; identifying a plurality of categories for categorizing the multiple transactions; for each category in the plurality of categories, using a processor to determine a percentage of a total value of the first user's transactions with the first payee that is allocable to the category; using the processor to aggregate the plurality of categories and each category's percentage to form a first user-specific model transaction; storing the first user-specific model transaction on a computer readable data storage device; identifying a new transaction conducted by the first user with the first payee; automatically splitting the new transaction based on the first user-specific model transaction; and electronically displaying the automatically split transaction for the user.