Bills of sale do not require notarization in the state of Illinois, but it is always an option. The quick answer is, usually, no.Generally when you sell your car, you won't need to worry about notarization. Though they are not legally required, a bill of sale adds a new layer of protection during a transaction. Prepare a bill of sale for the buyer. Include the date of sale and the price paid. Most states in the US do not require a notary or public official to witness and authenticate the signing of a bill of sale. Does a vehicle bill of sale have to be notarized in Illinois? No. When you privately sell a car in Illinois, the Bill of Sale does not need to be notarized. While a bill of sale is generally valid without notarization, there are situations where it becomes a wise precaution.