Clearly print or type all information, except signatures. Instructions. The new owner's social security number, taxpayer identification number (TIN), or federal employer identification number (EIN) is required.Below, we've outlined the five steps and forms required for how to sell a car in the state of New Jersey so you can sell your car quickly for the most cash. Complete the Questionnaire and Purchaser's Affidavit. You also may have the seller complete the Seller's Affidavit confirming the purchase price. § 403-4 Owner of private property. What information do I need to complete a bill of sale? Many standard forms are available below. All forms are categorized into their respective departments.