California’s Air Resources Board regulates trucks through three overlapping programs, and the California CARB regulations for trucks reach almost anyone who owns, operates, or manufactures medium- and heavy-duty vehicles in the state. The Advanced Clean Fleets rule forces fleet owners to buy zero-emission vehicles on a set schedule. The Advanced Clean Trucks rule requires manufacturers to sell a growing share of zero-emission models. The Clean Truck Check program subjects nearly every heavy-duty vehicle on California roads, including out-of-state trucks passing through, to periodic emissions testing. Miss any of them and the penalties stack per vehicle, per day.
Advanced Clean Fleets: Who Has to Buy Zero-Emission Trucks
The Advanced Clean Fleets regulation, codified at 13 CCR § 2015, applies to three groups: drayage operators, high-priority fleets, and state and local government agencies. Each has its own timeline, but all point the same direction — a mandatory shift from diesel to zero-emission technology.1Legal Information Institute. California Code of Regulations Title 13 Section 2015 – High Priority and Federal Fleets Applicability, Definitions, and General Requirements
Drayage Trucks
Drayage trucks — the short-haul vehicles moving containers at seaports and intermodal railyards — hit the first deadline. As of January 1, 2024, only zero-emission trucks can be newly registered in CARB’s TRUCRS reporting system for drayage work. Diesel drayage trucks already registered by December 31, 2023, can keep running until they reach their minimum useful life, which CARB defines as 13 years from the engine’s model year, and up to 18 years or 800,000 miles, whichever comes first. By 2035, every drayage truck entering a California seaport or railyard must be zero-emission, regardless of registration date.
High-Priority Fleets
If your company owns or operates 50 or more vehicles, or brings in $50 million or more in gross annual revenue (including subsidiaries), CARB classifies you as a high-priority fleet. You must choose one of two compliance paths.
- The ZEV Milestones Option requires your fleet to hit specific zero-emission vehicle percentages by target years, broken into vehicle groups. Lighter vehicles like box trucks and vans reach a 10 percent ZEV requirement by 2025, scaling to 100 percent by 2035. Heavier equipment like sleeper cab tractors follows a slower timeline, starting at 10 percent by 2030 and reaching 100 percent by 2042.2California Air Resources Board. Advanced Clean Fleets Regulation – ZEV Milestones Option
- The Model Year Schedule removes older trucks from your fleet according to a phase-out schedule tied to model year, instead of tracking ZEV percentages. CARB evaluates compliance against this schedule for fleets that report late.3Legal Information Institute. California Code of Regulations Title 13 Section 2015.6 – High Priority and Federal Fleets Enforcement
State and Local Government Fleets
Public agencies face a straightforward purchase mandate. Starting January 1, 2024, at least 50 percent of a government fleet’s annual vehicle purchases must be zero-emission. That jumps to 100 percent on January 1, 2027, after which a public agency cannot buy a new diesel or gas truck.4California Air Resources Board. State and Local Government Agency Fleet Requirements Overview Government fleets can also opt into the ZEV Milestones schedule instead of the purchase mandate.
Extensions When Infrastructure Isn’t Ready
CARB built in relief for fleet owners who run into real-world obstacles. The main tool is the ZEV Infrastructure Delay Extension, which buys time when charging or hydrogen fueling equipment isn’t ready despite your best efforts. To qualify, you must have started the infrastructure project at least a year before your compliance date and show that the delay resulted from circumstances beyond your control, such as equipment shipping problems, utility power shortages, unexpected construction issues, or even archaeological discoveries at the site. Depending on the cause, the extension can last two to five years.5California Air Resources Board. Zero-Emission Vehicle Infrastructure Delay Extension
Fleet owners who contract with a third-party charging provider can qualify too, but only if a signed contract of at least one year was already in place before the qualifying delay. Extensions specifically for utility power delays sunset on January 1, 2030.
Advanced Clean Trucks: The Manufacturer Rule That Shapes Your Options
The Advanced Clean Trucks regulation at 13 CCR § 1963 pushes manufacturers rather than fleet owners. Any company that certifies on-road vehicles over 8,500 pounds gross vehicle weight rating for sale in California must sell a growing percentage of zero-emission units each year.6Legal Information Institute. California Code of Regulations Title 13 Section 1963 – Advanced Clean Trucks Purpose, Applicability, Definitions, and General Requirements
Targets differ by vehicle class and ramp up through 2035. For 2026, manufacturers must ensure 10 percent of Class 2b–3 vehicles, 13 percent of Class 4–8 straight trucks, and 10 percent of Class 7–8 tractors sold in the state are zero-emission. By 2030, Class 4–8 trucks hit a 50 percent ZEV sales target. By 2036, every class reaches 100 percent, and manufacturers can no longer sell new diesel trucks of any size in California.
The mechanism is credits and deficits. Selling diesel trucks into California generates deficits; selling zero-emission trucks earns credits. A manufacturer is compliant when total credits equal or exceed total deficits. Surplus credits can be banked or traded. Credits and deficits only count when a vehicle is actually delivered to a buyer in the state.
This rule matters for fleet owners even though it technically binds manufacturers. It determines how many zero-emission trucks reach California dealer lots in any given year, which shapes what you can actually buy against your own compliance deadlines.
Clean Truck Check: Emissions Testing for Nearly Every Heavy Truck
The Clean Truck Check program, formally the Heavy-Duty Inspection and Maintenance program under 13 CCR § 2193, is the emissions testing regime for diesel and alternative fuel vehicles with a gross vehicle weight rating over 14,000 pounds operating on California roads. That includes vehicles registered outside California. If you drive through the state, you must comply.7California Air Resources Board. Clean Truck Check – FAQ
Testing Frequency
Most covered vehicles must pass emissions testing twice per year. The test depends on your engine’s age.8California Air Resources Board. Clean Truck Check Requirements for Vehicles Subject to Semi-Annual Compliance
- OBD-equipped vehicles (2013 and newer diesel engines, 2018 and newer alternative fuel engines) get scanned by a certified testing device that submits onboard diagnostics data to CARB electronically.
- Older diesel vehicles (2012 and older diesel engines) take a smoke opacity test along with a visual inspection of emissions control equipment.
- Older alternative fuel vehicles (2017 and older alternative fuel engines) require only a visual inspection.
Agricultural vehicles and California-registered motorhomes used for recreation or emergency occupancy test once per year. Starting October 2027, OBD-equipped vehicles move to quarterly testing, four times a year, which will affect most of the fleet on the road today.9California Air Resources Board. Clean Truck Check – Emissions Compliance Testing Requirements
Out-of-State Trucks
Trucks registered in other states are not exempt. If your vehicle operates on California public roads, you must register in the Clean Truck Check system, pay the annual compliance fee, and complete the required tests. CARB and the California Highway Patrol enforce this through roadside inspections at border crossings, ports, and railyards, and they use remote emissions monitoring devices and automated license plate readers to flag non-compliant vehicles statewide. Trucks that fail or skip testing can be denied entry at ports and railyards, which effectively shuts down a drayage operation.
Vehicles that fail an inspection must be repaired and retested before they can legally operate in the state. A narrow exemption exists for brand-new vehicles with engines certified to the most stringent optional NOx standard (0.01 g/bhp-hr or less), but it expires January 1, 2027.
Reporting Through TRUCRS and Clean Truck Check
Fleet owners interact with CARB through two online portals. The Truck Regulation Upload, Compliance, and Reporting System (TRUCRS) handles fleet data for the Advanced Clean Fleets and legacy Truck and Bus regulations.10California Air Resources Board. TRUCRS Reporting Information The Clean Truck Check system manages inspection results and vehicle compliance status separately. You may need accounts in both.
TRUCRS reporting calls for the VIN of each truck, the engine family name from the emission control label, engine model year, fuel type, gross vehicle weight rating, and primary base of operations. Business identifiers, including your California Secretary of State number and federal employer identification number, tie vehicles to a legal entity.
The Clean Truck Check system asks for similar vehicle details plus owner contact information. An annual compliance fee applies. As of 2025 the fee is approximately $31 per vehicle, and it must be paid for each truck before the vehicle is considered compliant. After registration and payment, the system generates a compliance confirmation drivers should keep accessible for roadside stops and gate checks.
Both systems need updating whenever you buy, sell, or retire a vehicle. Letting a profile go stale is one of the easiest ways to trigger a late-reporting violation, and CARB now assesses those penalties on a per-vehicle, per-month basis.
Penalties for Non-Compliance
Under the California Health and Safety Code, any person who violates an air quality rule faces strict liability of up to $5,000 per day. If CARB shows the violation was intentional or negligent, the ceiling rises to $10,000 per day. Violations that cause actual injury to public health can reach $15,000 per day. Each day the violation continues counts as a separate offense.11California Legislative Information. California Health and Safety Code Section 42402
Under the Advanced Clean Fleets enforcement provisions, late reporting is penalized separately for each vehicle and each month the required information stays unsubmitted. CARB will also evaluate compliance based on the Model Year Schedule for fleet owners who miss reporting deadlines, which can trigger additional penalties for running vehicles that should have already been retired.3Legal Information Institute. California Code of Regulations Title 13 Section 2015.6 – High Priority and Federal Fleets Enforcement
Real enforcement actions show the scale. In 2024, Amazon Logistics settled for $3.2 million after failing to verify that hired trucks complied with the Truck and Bus Regulation. That same year, CARB and the California Attorney General reached a settlement with engine manufacturer Cummins for $164 million in state penalties over illegal defeat devices in roughly 97,000 California engines.12California Air Resources Board. Enforcement Data Portal
Incentives That Offset the Cost of Going Zero-Emission
The price gap between diesel and zero-emission trucks is real, and several programs help close it. The most widely used is the Hybrid and Zero-Emission Truck and Bus Voucher Incentive Project (HVIP), which provides point-of-sale discounts through participating dealers. Vouchers for straight trucks currently range from $15,000 to $120,000 depending on vehicle class.13California HVIP. California HVIP – Clean Truck and Bus Voucher Incentive
Other state programs target specific fleet sizes or use cases.14California Air Resources Board. Incentives and Funding – TruckStop
- The Innovative Small e-Fleet Pilot Project provides HVIP-funded access to zero-emission vehicles through short-term leases, rentals, and truck-as-a-service models for fleets of 20 or fewer vehicles.
- The Zero-Emission Truck Loan Pilot Project helps small-business fleets access affordable financing by subsidizing lender risk.
- The Carl Moyer Program, administered by local air districts, funds replacement of older vehicles with cleaner technology.
- EnergIIZE Commercial Vehicles covers incentives for building charging or hydrogen fueling stations serving medium- and heavy-duty fleets.
- Low Carbon Fuel Standard credits give fleets running on electricity or hydrogen a tradeable revenue stream that lowers operating costs.
On the federal side, the Commercial Clean Vehicle Credit under the Inflation Reduction Act previously offered up to $40,000 per vehicle for trucks with a gross vehicle weight rating of 14,000 pounds or more, but that credit expired for vehicles acquired after September 30, 2025.15Internal Revenue Service. Commercial Clean Vehicle Credit The EPA’s Clean Heavy-Duty Vehicles Grant Program provided replacement funding through local governments and school districts, and its most recent application window has closed.16U.S. Environmental Protection Agency. Clean Heavy-Duty Vehicles Grant Program Both are worth checking periodically in case Congress reauthorizes or replaces them.