Which counties
Texas cities that lie partly inside and partly outside an emissions county
Updated Oct 7, 2026 · sources read Oct 6, 2026 · 2 official sources quoted
Short answer
Whether you need an emissions test depends on the county where the vehicle is registered, not the city on your address. Census boundaries and 2020 population counts show residents of cities such as Austin, Katy, Baytown, Elgin and Schertz living in counties outside the program.
County, not city
Every official statement of the rule is written by county. TCEQ’s registration-denial rule names counties, and TxDMV’s registration pages list counties.
Motorists with vehicles registered in Brazoria, Collin, Dallas, Denton, Ellis, El Paso, Fort Bend, Galveston, Harris, Johnson, Kaufman, Montgomery, Parker, Rockwall, Tarrant, Travis, and Williamson Counties will not be eligible to renew their vehicle's annual registration if the vehicle has not passed its annual emissions inspection or complied with the vehicle emissions inspection program requirements.
If you live in one of the following emissions counties you will need to obtain a passing vehicle emissions inspection before attempting to register your vehicle
Cities that cross the line
We asked the U.S. Census Bureau’s TIGERweb map service which incorporated places overlap both a program county and a county outside the program (a shared boundary alone does not count), then counted the 2020 Census population of each county part. Many overlaps turned out to be uninhabited slivers: open land, a highway edge or water. We list a city only when at least 50 residents live on each side of the line; each links to a page with the counties involved, the residents in each part and the station listings found in its program-county part.
- AustinTested: Travis and Williamson · Not tested: Hays (about 971 residents)
- BartlettTested: Williamson · Not tested: Bell (about 697 residents)
- BaytownTested: Harris · Not tested: Chambers (about 4,900 residents)
- CressonTested: Johnson and Parker · Not tested: Hood (about 717 residents)
- ElginTested: Travis · Not tested: Bastrop (about 8,076 residents)
- Fair Oaks RanchTested: Bexar · Not tested: Comal (about 1,306 residents) and Kendall (about 2,134 residents)
- KatyTested: Fort Bend and Harris · Not tested: Waller (about 4,447 residents)
- MabankTested: Kaufman · Not tested: Henderson (about 1,226 residents)
- Mineral WellsTested: Parker · Not tested: Palo Pinto (about 14,656 residents)
- Mustang RidgeTested: Travis · Not tested: Caldwell (about 449 residents)
- Royse CityTested: Collin and Rockwall · Not tested: Hunt (about 2,148 residents)
- SchertzTested: Bexar · Not tested: Comal (about 1,700 residents) and Guadalupe (about 34,637 residents)
- SelmaTested: Bexar · Not tested: Comal (about 290 residents) and Guadalupe (about 3,515 residents)
- WallerTested: Harris · Not tested: Waller (about 1,994 residents)
Residents: 2020 Census blocks inside each city’s current limits (U.S. Census Bureau TIGERweb). County parts with fewer than 50 residents are left out, so 24 cities whose only part on one side of the line is that small are not listed.
A city boundary is not a mailing address. A home with an Austin mailing address can sit outside the city limits. Check the county on your registration renewal notice or with your county tax office.
The main examples
Austin. The city lies mostly in Travis and Williamson counties, both in the program. Its southern edge reaches into Hays County, which is not, and close to a thousand Austin residents live there (2020 Census).
Katy and Baytown. Katy lies in Harris and Fort Bend counties and also in Waller County; Baytown lies in Harris County and also in Chambers County. Waller and Chambers are not program counties, and thousands of residents of each city live on that side of the line.
Schertz, Selma and Fair Oaks Ranch. From November 1, 2026 Bexar County is a program county. These cities reach into Guadalupe, Comal or Kendall County, none of which is in the program; most Schertz residents live in Guadalupe County.
Not on the list. Houston, San Antonio and Fort Worth also touch a county outside the program on the Census map, but the 2020 Census counted no one, or only a handful of people, in those parts. Cibolo (its Bexar County part) and Universal City (its Guadalupe County part) are the same. For those cities the county-line question does not arise in practice.
Austin Area: Travis and Williamson Counties
Houston-Galveston-Brazoria Program Area: Brazoria, Fort Bend, Galveston, Harris, and Montgomery Counties
San Antonio Area: Bexar County (beginning on November 1, 2026)
What to do
Check the county of registration on your renewal notice, or ask your county tax office. Then use the county checker. If you have just moved within one of these cities, the county of your new address decides which rule applies once the vehicle is registered there.
Questions
I live in Austin. Do I need an emissions test?
If the vehicle is registered in Travis or Williamson County, yes. If it is registered in Hays or Bastrop County, no: in the Austin area TCEQ lists only Travis and Williamson counties.
Austin Area: Travis and Williamson Counties
Does a Katy address in Waller County need a test?
No. Waller County is not one of the program counties. Katy addresses in Harris or Fort Bend County do need the test.
Houston-Galveston-Brazoria Program Area: Brazoria, Fort Bend, Galveston, Harris, and Montgomery Counties
Which county counts if I work in one county and live in another?
The county where the vehicle is registered. TCEQ’s registration-denial rule is written for vehicles registered in the program counties.
Motorists with vehicles registered in Brazoria, Collin, Dallas, Denton, Ellis, El Paso, Fort Bend, Galveston, Harris, Johnson, Kaufman, Montgomery, Parker, Rockwall, Tarrant, Travis, and Williamson Counties will not be eligible to renew their vehicle's annual registration if the vehicle has not passed its annual emissions inspection or complied with the vehicle emissions inspection program requirements.
Sources
- TCEQ, Vehicle Emissions Inspections in Texaspage as published Sep 23, 2026 (archived copy), read Oct 6, 2026
- TxDMV, New to Texasread Oct 6, 2026
TX Emissions Guide is an independent guide, not a government site. Spotted something out of date? Report a correction.