Signature of Registered Owner. Authorization Letter.Please complete this printable form online or write legibly in blue or black ink ONLY. Edit, sign, and share authorization letter harris county online. No need to install software, just go to DocHub, and sign up instantly and for free. How to fill out the Harris County Tax Office Authorization Form? 1. Enter business or individual's name. 2. If you have any questions or need assistance completing the Authorization, you can call (713). 970-7330. If the document you are filing is from a Texas court, it must be a complete original court-issued certified copy. "(Personalized Seal)" in the following examples means a seal containing the words "Notary Public, State of Texas" around a star of five points, the notary.