No. Notarization is not mandatory. However, in long lines of cases decided by the Supreme Court, the notarization of a document has a substantial legal effect. It converts a private document to a public record and becomes admissible in court without further proof of its authenticity. When a case is filed against the maker to honor the promissory note, the usual defense for non-payment is that his or her signature is forged; the maker did not understand the contents of the document he or she signed; the maker’s consent was vitiated, or was forced to sign the document. If the promissory note is notarized, the maker cannot, later on, allege that he did not sign the document. As a notarized promissory note holder, you do not need to prove that the maker executed or signed the document. It is authentic on its face.