SACRAMENTO — Fleet owners subject to California Air Resources Board’s (CARB’s) medium and heavy-duty vehicle regulations must report annually to meet regulatory requirements. The reporting deadline is February 1, 2024


The Advanced Clean Fleets (ACF) regulation on “High Priority Fleets” applies to any contractor:

  1. Who owns, operates, or directs 50 or more covered vehicles, with at least one covered vehicle in California; or
  2. Has more than $50 million total gross annual revenue and operates at least one covered vehicle in California.


The regulation covers medium-duty and heavy-duty on-road vehicles with a gross vehicle weight rating greater than 8,500 pounds, off-road yard tractors, and light-duty package delivery vehicles. It does not apply to passenger vehicles and light duty passenger trucks. 


The ACF regulation is part of the California Air Resources Board’s (CARB) approach to accelerate a large-scale transition to zero-emission medium-duty and heavy-duty vehicles. This regulation works in conjunction with the Advanced Clean Trucks (ACT) regulation, approved in March of 2021, which pushes manufacturers to bring zero-emission vehicles (ZEV) to market. The ACF is the purchase mandate for fleets and the ACT is the sales mandate for truck manufacturers. The ACF regulation was promulgated under the authority of the Governor’s Executive Order N-79-20.


High priority fleets must phase zero-emission vehicles (ZEV) into their fleets, for covered vehicles, beginning in 2024 according to one of two available compliance pathways—the “Model Year Schedule” (which is the default compliance pathway) or the “ZEV Milestones Option” (which is the alternate, opt-in compliance pathway).

Option 1 – Model Year Schedule Timeline:

Compliance is achieved through zero-emission vehicle additions and the removal of existing ICE vehicles at the end of their useful life. Exemptions and delays are available for qualifying fleets.

    • Starting January 1, 2024, all additions of covered vehicles to a fleet must be zero-emission.
    • ICE vehicles must be retired after 18 years old or 800,000 miles, whichever comes first.

Option 2 – Zero-Emission Milestone Timeline:

Zero-emission vehicle percentage milestones as determined by preset vehicle groups. Fleets can add ICE vehicles to their fleet if they reach the zero-emission percentage milestones outlined in the chart below.

A chart outlining the percentage of vehicles that must be zero-emission



The Advanced Clean Fleets (ACF) regulation requires High Priority Fleets to report their California fleet information through the Truck Regulation Upload, Compliance and Reporting System (TRUCRS) by February 1, 2024.

TRUCRS is the official reporting system for fleets to meet reporting and compliance requirements for all the following regulations: 

  • Advanced Clean Fleets Regulation 
  • Truck and Bus Regulation 
  • Zero-Emissions Airport Shuttle Regulation 
  • Solid Waste Collection Vehicle Regulation

Reporting guidance, regulation language, advisories, fact sheets, and other compliance tools can be accessed through the Advanced Clean Fleets, Registration and Reporting webpage.


The 2021 and 2022 State budgets include a total investment of $10 billion over 6 years to reduce CO2 emissions from the transportation sector by supporting ZEVs and ZEV infrastructure. This funding has been administered by CARB, the California Energy Commission, the California State Transportation Agency, and the Governor’s Office of Economic and Business Development. It includes funding for the Hybrid and Zero-Emission Truck and Bus Voucher Incentive Project (HVIP) which provides funding for the purchase of clean trucks. You can review the program here:


If a fleet owner cannot comply because a ZEV (or near-zero emission vehicle (NZEV)) is not available in the needed configuration, the owner may purchase a new internal combustion engine (ICE) vehicle with a California certified engine.

Starting in 2025, CARB will maintain a ZEV Purchase Exemption List with common vehicle body configurations that are not available to purchase as a ZEV or NZEV. Fleet owners will be able to purchase new ICE vehicles of the listed configurations without applying for an exemption in advance. However, this list will not include vehicles that are already available as ZEVs like pickups, buses, box trucks, vans, or tractors.

Information about ICE vehicles purchased under this exemption must be reported in the TRUCRS System when the vehicle is received. If an available ZEVs or NZEVs cannot be configured to meet the primary intended function or there is a safety conflict, the fleet owner may apply for a fleet specific exemption by submitting their request with supporting information by email. This exemption applies to the Model Year Schedule, the ZEV Milestones Option, and the ZEV Purchase Schedule.

Additionally, if a fleet owner has ordered a ZEV for immediate delivery at least one year ahead of the next compliance date, but it doesn’t arrive in time to meet their compliance requirements, the fleet owner may request this extension at the beginning of the applicable compliance year by submitting proof of purchase by email. The extension allows an existing vehicle to continue operating until the ZEV is received without affecting compliance. This extension applies to drayage trucks, the Model Year Schedule, and the ZEV Milestone Option; but is not relevant for fleets that comply with the ZEV Purchase Schedule.

You can review more information on regulation exemptions and extensions HERE.


If the fleet owner begins a project to install ZEV fueling infrastructure (charging or hydrogen fueling stations) at their facility, or dedicated parking location, at least one year ahead of the next applicable compliance date, the fleet owner may receive an extension to continue operating existing vehicles until the project is completed.

The extension for a construction delay could be granted for up to two years and for a site electrification delay for up to five years depending on the specific circumstances. Eligible vehicle owners can submit their request with supporting information by email. Applies to: Model Year Schedule, the ZEV Milestones Option, the ZEV Purchase Schedule, and drayage trucks.


Information about the ACF is available at the ACT Website: If you have questions, call (866) 634-3735 or email