The sole purpose of this form is to authorize the above named representative to complete the transaction indicated. 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. Vehicle Specific Authorization Letter. Please complete this printable form online or write legibly in blue or black ink ONLY, within the lines provided. How to fill out the Harris County Tax Office Authorization Form? 1. Enter business or individual's name. 2. Looking for Authorization Letter Maker to fill? 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.