What do I do with the document in the yellow envelope I received in the mail?

That is your personal property rendition. It is mailed the first week of January every year. It needs to be reviewed, if any changes need to be made to the personal property items listed or any new items need to be listed, make all the necessary corrections on the sheet. Sign & date the first page, then mail or deliver it back to the Appraiser’s office before March 15th . Even if no changes need to be made it is mandatory you return the signed rendition to prevent a tax penalty.