A purchaser of the assets of a business will be liable for any unpaid sales tax of the seller, as well as any accrued interest and penalties related thereto. Agreement to Sell and Purchase.An Asset Purchase Agreement is an agreement between a buyer and a seller of a business as to the terms and conditions of the sale of the business. A business purchase agreement is any type of legal contract governing the transfer of a business or its assets from one owner to another. This Agreement is for the purchase of assets only, and.