Jurisdiction Basics
City Limits vs. ETJ vs. Unincorporated Travis County
Where your property sits — inside city limits, in an ETJ, or in unincorporated county land — determines which rules apply.
Inside Austin's city limits, city laws and city services apply. Just outside those limits, up to five miles out, is the extraterritorial jurisdiction — called the ETJ. The ETJ is land that Austin can influence, such as requiring certain street and lot standards for new subdivisions. But it is not yet inside the city.
Beyond the ETJ is unincorporated Travis County. Out there, county rules apply instead of city rules. Travis County has its own development rules under Chapter 482 that cover subdivisions and drainage. If you are buying land or planning to build outside a city, find out whether your property is in an ETJ or in plain unincorporated county land. The rules are different. Call Travis County Transportation and Natural Resources at (512) 854-9383 to ask.
Source to confirm: Travis County – Development Requirements