Yes. Texas sales tax is due when your customer picks up or takes delivery of a taxable item in Texas. You can refund the tax collected to your customer.An international sales contract is an agreement between a buyer and a seller that identifies the parties in the transaction, the goods or services being sold. This Standard Document has integrated drafting notes with important explanations and drafting and negotiating tips. Sale of Goods Agreement. If a seller does not collect Texas tax, you can report it directly to our office. If you do not have a sales tax permit, you can file a use tax return (PDF). Sales tax applies to retail sales of certain tangible personal property and services. The purpose of the CISG is to provide a modern, uniform and fair regime for contracts for the international sale of goods. While in the zone, merchandise is not subject to U.S. duty or excise tax.