Abstract: The invention relates to a computer-implemented system and method for uniquely identifying a merchant from a transaction string transmitted by a payment network. The method may comprise the steps of: gathering input information, including receiving the transaction string from the payment network and receiving from a data provider a data set containing merchant information; cleansing the transaction string; executing a match process between the transaction string and the data set from data provider to find the best merchant match; wherein the match process comprises using a logistic regression model, a waterfall process, or an override process; consolidating results of the matching process to create a master lookup table having attributes from transaction strings mapped to matching merchant attributes from the data provider data set; and executing a transaction tagging process on a received transaction string.