Certain implementations include systems and methods for combined one-time-passcode (OTP) and knowledge-based-authentication (KBA) identity authentication. A method is provided that includes receiving a set of identity information associated with a subject; querying one or more databases; receiving personally identifiable information; producing at least one knowledge based authentication (KBA) identity proofing question having a personally identifiable correct answer; generating a unique correct one-time pass (OTP) code for the personally identifiable correct answer; generating one or more incorrect answers with corresponding incorrect codes; outputting, the at least one KBA identity proofing question; outputting the personally identifiable correct answer with the unique correct OTP code, and the one or more incorrect answers with corresponding incorrect codes; receiving a response code; comparing the response code and the unique correct OTP code; and responsive to a match between the response code and the unique correct OTP code, outputting a first indication of authentication.