For most private vehicle sales between individuals, a bill of sale does not need to be notarized to be considered legally valid and binding. You simply write them a bill of sale.The signer must always appear before the Notary during the notarization in California. While a bill of sale is generally valid without notarization, there are situations where it becomes a wise precaution. Does a vehicle bill of sale have to be notarized in California? No. When you privately sell a car in California, the Bill of Sale does not need to be notarized. The Notary Public Handbook is designed to supplement your course of study, which will prepare you for the notary public examination.