Any person buying or accepting a car in New York must: Sign the bill of sale; Pay sales tax or present proof of exemption; Register and title the vehicle. This form certifies the purchase price and determines the sales tax you must pay when registering the vehicle.Use SmartAsset's free New York mortgage loan calculator to determine your monthly payments, including PMI, homeowners insurance, taxes, interest and more. Download your car bill of sale document among 40 customizable templates. Protect your vehicle sale transaction. Some dealers are bad and will play games to get more down or higher payments. Your tax refund could offer a unique opportunity to make a sizable down payment that lowers your monthly vehicle bill. How much can I save?