Texas Assumed Name Form Instructions are the guidelines for filing a form to register a "doing business as" name in the state of Texas. The form is also known as an assumed name certificate, d/b/a (doing business as) certificate, or fictitious name certificate. There are two types of Texas Assumed Name Form Instructions: one for filing with the County Clerk's Office, and one for filing with the Secretary of State's Office. When filing with the County Clerk's Office, the instructions require the applicant to provide the business name, owner's name, address, and purpose of the business. The form must be signed by the owner and notarized. When filing with the Secretary of State's Office, the instructions require the applicant to provide the business name, owner's name, address, and purpose of the business. The form must be signed by the owner and must include a filing fee. The instructions for both types of forms include the information necessary to complete the form, and the applicable filing fees.