California Air Resources Board

Accelerating zero-emissions truck markets

ACF is part of CARB’s overall strategy to accelerate a large-scale reduction in tailpipe emissions focusing on zero‑emissions medium- and heavy-duty vehicles. This regulation works in conjunction with the Advanced Clean Trucks regulation, approved in 2021, which helps ensure that zero‑emissions vehicles (ZEV) are available for sale. The regulation is critical to achieving both our health-protective ambient air quality standards and the State’s climate goals, and is expected to save $26.5 billion in statewide health benefits and provide a net cost savings of $48 billion to fleets.

Which fleets does the ACF regulation affect?

The regulation applies to trucks performing drayage operations at seaports and railyards, fleets owned by State, local, and federal government agencies, and high priority fleets. High priority fleets are those entities that own, operate, or direct at least one vehicle in California, and that have either $50 million or more in gross annual revenue, or that own, operate, or have common ownership or control of a total of 50 or more vehicles. The regulation affects medium- and heavy-duty on-road vehicles with a gross vehicle weight rating greater than 8,500 pounds, off-road yard tractors, and light-duty mail and package delivery vehicles.

How will this regulation affect existing trucks or equipment?

High priority and federal government fleets, simply referred to as high priority fleets for the remainder of this document, can comply with either a default Model Year Schedule or opt-in to the ZEV Milestone Option. The Model Year Schedule allows fleet owners to continue using existing trucks until the end of their useful life, defined as the later of either: 1) 13 years, beginning with the model year that the engine in the vehicle and was first certified for use by CARB or United States Environmental Protection Agency (U.S. EPA), or 2) the date that the vehicle exceeds 800,000 vehicle miles traveled or 18 years from the model year that the engine in the vehicle was first certified for use by CARB or U.S. EPA (whichever is earlier). High Priority Fleets using the Model Year Schedule need to remove internal combustion engines from the California fleet by January 1 of the calendar year after their minimum useful life mileage thresholds are exceeded, or January 1 of the calendar year the engine model year is 18 years old, whichever occurs first. Under the Model Year Schedule, all new additions to the California fleet must be ZEVs. Fleet owners may alternatively choose the ZEV Milestones Option which allows fleets full flexibility to manage their fleet composition over the phase-in period, as long as the ZEV Milestone targets are met. State and local government fleets may keep their existing vehicles past the end of the vehicle's useful life, but must either follow a default zero-emissions purchase requirement or opt-in to the ZEV Milestones Option. As drayage trucks reach their minimum useful life, they will be required to reduce tailpipe emissions by using zero-emission vehicles. All drayage trucks will be required to be zero-emissions by 2035. Additionally, there are a number of exemptions and extensions that are applicable for certain fleet types and circumstances.

What are the different components of ACF?

• Manufacturer sales mandate. Manufacturers may sell only zero-emissions medium- and heavy-duty vehicles in California starting in 2036.
• Drayage fleets. Drayage trucks are in-use Class 7 and 8 on-road vehicles that transport containers and bulk goods to and from seaports and intermodal railyards. Land ports of entry, which provide controlled entry to or departure from the United States, are not considered seaports or intermodal railyards. Beginning December 31, 2023, trucks must be registered in Truck Regulation Upload, Compliance, and Reporting System (TRUCRS) to conduct drayage activities in California. Non-zero-emissions “legacy” drayage trucks may register in TRUCRS through December 31, 2023. Legacy drayage trucks can continue to operate through their minimum useful life. Beginning January 1, 2024, only zero-emissions drayage trucks may register in TRUCRS. All drayage trucks entering seaports and intermodal railyards are required to be zero-emissions by 2035.
• High priority and federal fleets. High priority and federal fleets may purchase either ZEVs or near-ZEVs, or a combination of ZEVs and near-ZEVs, until 2035. Starting in 2035, only ZEVs will meet the requirements. These fleets must initially submit a compliance report by February 1, 2024 and comply with the Model Year Schedule or may elect to use the optional ZEVMilestones Option to phase ZEVs into their California fleets.
  • Model Year Schedule: Fleets must purchase only ZEVs beginning 2024 and, starting January 1, 2025, must remove internal combustion engine vehicles at the end of their useful life, as specified in the regulation.
  • ZEV Milestones Option (Optional): Instead of the Model Year Schedule, fleet owners may elect to meet ZEV targets as a percentage of the total fleet starting with vehicle types that are most suitable for electrification.
• State and local agencies. California State and local government fleets, including city, county, special district, and State agency fleets, would be required to ensure 50 percent of vehicle purchases are zero-emissions beginning in 2024 and 100 percent of vehicle purchases are zero-emissions by 2027. They must also initially submit a compliance report by April 1, 2024. Small government fleets of 10 or fewer vehicles and those in designated counties would start their ZEV purchases beginning in 2027. Alternatively, State and local government fleet owners may elect to use the ZEV Milestones Option. State and local government fleets may purchase either ZEVs or near-ZEVs, or a combination of ZEVs and near-ZEVs, until 2035. Starting in 2035, only ZEVs will meet the requirements.

This document is provided to assist regulated entities in complying with the Advanced Clean Fleets regulation. In the event any discrepancy exists between this document and the Advanced Clean Fleets regulation, the regulatory text of the Advanced Clean Fleets regulation applies.