All mechanic's liens must be filed at the main Dallas County Tax Office at 500 Elm Street, Suite 1200, Dallas, TX 75202. To add or remove a lien on your vehicle title, visit your local county tax office.Fill Out Form 130U: The buyer completes this application form, available online or at local tax offices. A Bill of Sale from the out of state seller can be provided instead. This howto guide provides a starttofinish explanation on how to file a Texas mechanics lien and even includes free downloads of important forms.