I have a customer that is adamant that they shouldn't be billed for sales tax because they are paying the sales tax on the full amount of the project but can't supply me with a direct pay certificate. I went through a tax audit last year and they confirmed I was doing everything correctly in regards to a rental as stated in the Texas Comptroller ruling #3.294, so no tax due. I believe that they should remove all rentals from their project and pay the sales tax on the balance. So they have paid for everything except for the sales tax billed. Can I file a lien on just the taxes due?