Why do documents need to be notarized? Certain documents must be notarized in order to have legal effect. Given the inherent formal and corresponding significance of this subject of legal documents that must be notarized, state governments have deemed it necessary to enlist a trained individual to assist with their execution. A "notary public," following his or her official appointment, a notary public performs as a quasi-public officer to attest to the proper execution of these important documents. Types of documents that may require notarization: Wills Trusts Deeds Contracts Affidavits I-9 Employment Loans Leases & More: Be Prepared for Your Notary Visit: Bring a valid, government-issued photo ID with you when you visit. Call or SMS.