A computer system for identifying merchant category code misclassifications includes at least one processor in communication with a transaction database and a high-risk merchant database. The transaction database stores transaction records by a plurality of account holders. The high-risk merchant database stores high-risk merchant records each associated with high-risk merchants. The processor queries the transaction database for transaction records and calculates a high-risk cardholder metric for each of the account numbers. The at least one processor further queries the transaction database for transaction records including (i) the account number of high-risk cardholders, and (ii) a merchant identifier associated with other than the plurality of high-risk merchants, to retrieve a second set of transaction records. The at least one processor further calculates a high-risk merchant metric for each of the merchant identifiers, identifying a MCC misclassified merchant.