Register your business name in the county in which you will do business.
Dallas County Clerk, Assumed Name (DBA)
State Requirements for Assumed Business Name Certificate
A domestic or foreign corporation, limited liability company, limited partnership, limited liability partnership, or other foreign filing entity that regularly conducts business or renders a professional service in this state under a name other than its legal name (the name stated in its certificate of formation or comparable document) must file an assumed name certificate with the secretary of state and with the county clerk in the appropriate county.
Contact the Texas Secretary of State Office for information: (512) 463-5555