Short answer: In 2026 most heavy-duty trucks must pass a Clean Truck Check test twice a year. For California-registered trucks, the deadlines are the DMV registration expiration date and six months after it. You may test up to 90 days before each deadline. Beginning October 2027, trucks with onboard diagnostics (OBD: 2013+ diesel and 2018+ alternative fuel) move to four tests a year. California-registered (non-commercial) motorhomes and agricultural vehicles stay at once a year.
Some websites say quarterly testing starts January 1, 2027. CARB's FAQ and the regulation say October 2027.
How your deadline is set
| Vehicle | Deadline schedule |
|---|---|
| Registered in California | DMV registration expiration date, then every six months |
| Registered outside California, or DMV-exempt (government) plates | Set by the last digit of the VIN (CARB's Table II) |
| California-registered motorhome | Once a year |
| Agricultural vehicle (farm business, used only in agriculture) | Once a year |
Your exact dates are shown in your CTC-VIS account. Check them there; CARB is the only official source.
The 90-day testing window
CARB accepts a test submitted no more than 90 days before a compliance deadline. Example from CARB: for a February 1, 2025 deadline, testing could start November 3, 2024. A test inside the 90-day window covers that deadline; a test earlier than that does not count toward the next one, so plan your test dates.
Free reminders: enter your next deadline on CTC Finder reminders and get an email 30 days and 7 days before each test is due.
Timeline
| Date | What changed |
|---|---|
| January 1, 2023 | Regulation operative; roadside emissions screening (REMD) begins |
| October 1, 2023 | CTC-VIS opens for vehicle reporting and fees (initial deadline extended to January 31, 2024) |
| October 1, 2024 | Periodic emissions testing takes effect |
| January 1, 2025 | Deadlines from this date require a passing test |
| January 1, 2026 | Annual compliance fee rises to $32.13 per vehicle |
| January 1, 2027 | Annual compliance fee rises to $33.12 per vehicle |
| October 2027 | OBD vehicles move to four tests a year; non-OBD trucks stay twice a year |
What quarterly testing means for fleets
Doubling the number of tests doubles the number of tester visits. For a fleet of 20 OBD trucks that is 80 tests a year instead of 40. Two ways fleets keep the cost down:
- Mobile testers who test many trucks per visit and offer fleet pricing. 2,543 businesses on CTC Finder offer mobile testing.
- Telematics devices certified by CARB (for example from Geotab, Samsara, Motive or Zonar) that a credentialed tester can use to upload OBD tests automatically.
Missed a deadline?
Get the test done as soon as possible and check CTC-VIS for notices. Non-compliance can lead to a DMV registration hold, notices of violation and civil penalties. See fines and penalties.
Sources
- CARB, Requirements for vehicles subject to semi-annual compliance
- CARB, Clean Truck Check FAQ
- 13 CCR § 2196.1, periodic testing requirements
- CARB, Annual vehicle compliance fee update for 2027
- CalMatters Digital Democracy, SB 1064 bill history (checked October 30, 2026)
Frequently asked questions
How often does a truck need Clean Truck Check in 2026?
Twice a year for most heavy-duty diesel and alternative-fuel trucks; once a year for California-registered motorhomes and agricultural vehicles.
When does Clean Truck Check go to 4 times a year?
CARB says OBD-equipped vehicles must test four times per year beginning October 2027. Older non-OBD trucks stay on twice-a-year smoke opacity tests.
How early can I do my Clean Truck Check test?
Up to 90 days before the compliance deadline.
Where do I find my Clean Truck Check due date?
Log in to CTC-VIS at cleantruckcheck.arb.ca.gov. For California trucks the deadlines are tied to the DMV registration expiration date.
Is there a once-a-year option for low-mileage trucks?
Not under current rules. A 2026 bill (SB 1064) proposed annual testing for very low-mileage trucks, but the Governor vetoed it on September 20, 2026, so it is not law. Check CARB for updates.
CTC Finder is an independent directory and is not affiliated with CARB. Rules change; check CARB's Clean Truck Check pages for the official version.