Knowledge-Based Authentication (KBA) verifies a signer’s identity by asking questions that only they should be able to answer — typically generated from credit bureau data (past addresses, vehicles owned, mortgage amounts). The signer must answer correctly to proceed.
KBA is required by the IRS for remote e-signatures on Form 8879. It’s also used in other regulated workflows (mortgage, financial services, healthcare). For accounting client portals, KBA is integrated into the e-signature workflow — the signer answers identity questions before signing, and the audit trail records the verification.