Embodiments of the invention detect fraudulently filed tax returns when a user prepares or submits a subject tax return that relates to a subject taxpayer for filing with a government taxing authority. Embodiments analyze tax information of various sources to determine whether the subject tax return is genuine (i.e., not fraudulent). The invention determines confidence indicators based upon some or all of a source location, a source type, data entry characteristics, refund vehicle characteristics, internal consistencies, external historical consistencies, external lateral consistencies, user authentication methods, and a taxpayer risk level. Based upon these analyses the invention calculates a taxpayer identity confidence score, which may be utilized to allow or deny the filing of the subject tax return.