Austin-Round Rock program area
Emissions testing in Williamson County, Texas
Required for registration renewal
Williamson County is part of the Austin-Round Rock program area. A gasoline vehicle from 2 through 24 years old registered here needs a passing on-board diagnostics (OBD) emissions test before its registration can be renewed, and stations may charge up to $11.50. TxDMV counted 574,108 vehicles registered in Williamson County in its fiscal year 2025 (September 2024 through August 2025). Our search of public map listings found 3 businesses in the county that name inspections or emissions testing.
Key facts
- OBD testing from
- Sep 1, 2005
- Station fee (max)
- $11.50
- State fees at registration (most vehicles)
- $2.75 + $7.50
- Waiver repair minimum
- $600
- Vehicles registered (FY 2025)
- 574,108
- Stations, Austin area (TCEQ, 2023)
- 432
- Listings on this page
- 3
- Tax office
- Georgetown
- Neighbors without testing
- 5
Who must test in Williamson County
TCEQ lists Williamson County in the Austin-Round Rock program area with Travis. Enhanced (OBD) testing applies here from September 1, 2005. The test applies by fuel and age, and only to vehicles registered in the county.
Austin Area: Travis and Williamson Counties
Travis and Williamson Counties implemented enhanced inspections on September 1, 2005.
Gasoline vehicles model-year 2 through 24 years old are inspected annually beginning with the vehicle's second anniversary.
Not required to inspect: electric vehicles, diesel vehicles, motorcycles, and mopeds.
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.
What the test costs in Williamson County
The station may charge at most $11.50 for the OBD test, less than the $18.50 cap around Dallas-Fort Worth and Houston. The state’s share comes with the registration renewal: TxDMV’s sample notice lists the $2.75 emissions inspection fee, and most non-commercial vehicles also pay the $7.50 inspection program replacement fee there (the law exempts some, such as vehicles with antique plates; see the replacement fee). The fee calculator adds it up for your model year.
Where to get a test in Williamson County
3 business listings in 3 towns of Williamson County name inspections or emissions testing. For scale: TCEQ counted 432 active emissions stations in the Austin area (Travis and Williamson) in November 2023, so the listings here are a sample. The official list of certified stations is the DPS inspection station locator.
Table ES-2. Number of Texas Emissions Inspection Stations in the TIMS Database by Program Area and Station Type (November 2023)
The the Austin area (Travis and Williamson) row (test-only, test-and-repair, total)
ARR 125 307 432
These are businesses whose public map listing (Apple Maps or Yelp data, found through DuckDuckGo) names inspections, emissions testing or smog checks. A listing is not proof that the business is certified by the Texas Department of Public Safety, and the list is not complete: confirm with the station or the DPS inspection station locator before you go.
Cedar Park
1 listing
- Sticker Express1408 West Whitestone Blvd, Cedar Park, 78613(512) 992-1032
Georgetown
1 listing
- Mr. T's Automotive and Inspection2020 S Austin Ave, Georgetown, 78626(512) 955-6464
Liberty Hill
1 listing
- Hill Country Vehicle Inspection Pro’s123 Holmes Rd, Unit: 3, Liberty Hill, 78642(512) 548-6773
Renewing a registration in Williamson County
After the vehicle passes, renew online, by mail or at the Williamson County tax assessor-collector’s office. TxDMV’s directory lists the office in Georgetown.
Physical Address: 1848 Texas Trail Georgetown, TX 78626-5829
Telephone: (512) 943-1601
Website: www.wilcotx.gov
Your vehicle registration may be renewed online 90 days prior to the expiration date or up to 12 months after the expiration date if you have not received a citation for an expired registration.
If the vehicle fails
Repair it and go back to the same station within 15 days for a free re-test. If it still fails after at least $600 of emissions-related repairs, DPS may grant an Individual Vehicle Waiver; see waivers and time extensions.
You do not have to pay to get your vehicle re-inspected if it fails inspection. If your vehicle fails the inspection, have the item(s) repaired and take it back to the inspection station that originally performed the inspection within 15 days for a free re-test.
This waiver is available to a vehicle owner that has spent at least $600 ($450 in El Paso) on emission-related repairs and is still unable to pass an emissions inspection or unable to qualify for another type of waiver.
Cities on the Williamson County line
Census boundaries put these cities partly in Williamson County and partly in a county outside the program, with residents on both sides (2020 Census). A vehicle’s test depends on the county it is registered in, not the city.
Counties next to Williamson County
| County | Emissions test |
|---|---|
| Bastrop County | No |
| Bell County | No |
| Burnet County | No |
| Lee County | No |
| Milam County | No |
| Travis County | Yes |
Counties touching Williamson County: U.S. Census Bureau TIGERweb (January 1, 2026 vintage).
Williamson County questions
Does Williamson County require an emissions test?
Yes. A gasoline vehicle 2 through 24 years old registered in Williamson County needs a passing emissions test before the registration can be renewed.
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.
How much is an emissions test in Williamson County?
Up to $11.50 at the station. The state’s share is paid at registration: TxDMV lists a $2.75 emissions inspection fee, and most non-commercial vehicles also pay the $7.50 inspection program replacement fee ($16.75 once for a new vehicle).
Where is the Williamson County tax office?
The TxDMV directory lists 1848 Texas Trail, Georgetown, TX 78626-5829, telephone (512) 943-1601. Check the county’s website for other locations and hours before you go.
Which counties next to Williamson County do not test?
Bastrop County, Bell County, Burnet County, Lee County and Milam County are not in the emissions program (U.S. Census county boundaries; TCEQ program list). What counts is the county where the vehicle is registered.
Sources
- TCEQ, Vehicle Emissions Inspections in Texaspage as published Sep 23, 2026 (archived copy), read Oct 6, 2026
- Texas DPS, Cost of Inspectionpage as published May 19, 2026 (archived copy), read Oct 6, 2026
- TCEQ, Highlights of the Vehicle I/M Programpage as published Jun 16, 2026 (archived copy), read Oct 6, 2026
- TxDMV, Register Your Vehicleread Oct 6, 2026
- TxDMV, FY 2025 Vehicles Registered and License Fees by County and Regional Officeread Oct 6, 2026
- TxDMV, Williamson County Tax Office (TxDMV county tax office directory)read Oct 6, 2026
- TCEQ, Affidavit, Waivers and Extensions, and the Vehicle Inspection Reportpage as published Jun 24, 2026 (archived copy), read Oct 6, 2026
- Texas DPS, General Inspection (FAQ)page as published May 19, 2026 (archived copy), read Oct 7, 2026
- TCEQ, 2024 Fee Analysis for AirCheckTexas Vehicle Emissions Inspection Programpage as published Oct 5, 2025 (archived copy), read Oct 6, 2026
- U.S. Census Bureau TIGERweb, Texas county boundaries