A computer system is configured to provide a payment card security application programming interface (API) for providing a payment card security score to a partner entity computer system. Responsive to receipt of user identification data for a card holder from the partner entity computer system via the API, the computer system retrieves payment card electronic funds transfer (EFT) transaction data records corresponding to the card holder, and determines a transaction type and security level associated for the user's transactions. The computer system generates, based on the determined security level for each of the transactions, a security score for the card holder. The partner entity computer system provides the user identification data for the card holder to the payment card security API responsive to receipt of an authorization request for a new transaction. The partner entity computer system may determine whether to approve or deny the new payment card EFT transaction based upon the security score.