California Fleet Upgrades: 90-Day ACF Enforcement Guide for Government Fleets

California's 90-day ACF enforcement language needs to be understood in context. The California Air Resources Board (CARB) issued an enforcement notice stating that certain civil-penalty actions involving controlling parties could begin 90 days after the U.S. EPA took final action on California's ACF preemption-waiver request. However, that provision is different from the requirements applying to California state and local government fleets, which CARB states do not require the federal waiver to enforce.

For government fleet managers, the practical priority is therefore not simply counting down 90 days. It is understanding which ACF requirements apply to the fleet, what vehicles must be reported or replaced, which compliance pathway is being used, and how procurement decisions should support the fleet's requirements.

What Is the California Advanced Clean Fleets Regulation?

The Advanced Clean Fleets (ACF) regulation is California's framework for transitioning certain medium- and heavy-duty fleets toward zero-emission vehicles.

The regulation affects different fleet categories differently. CARB currently states that the state and local government fleet portion remains in effect, while portions covering high-priority and drayage fleets that require federal authorization are not currently being enforced. CARB also notes that recent amendments are expected to change parts of the regulation before January 2027.

For state and local government agencies, ACF can apply to vans, buses, trucks and other vehicles with a gross vehicle weight rating above 8,500 pounds, as well as certain light-duty package delivery vehicles.

That makes ACF relevant to government organizations planning fleet vehicle procurement, vehicle replacement and zero-emission fleet upgrades.

What Does the 90-Day ACF Enforcement Period Mean?

The 90-day language comes from CARB's enforcement notices concerning parts of the ACF regulation that depend on federal authorization.

CARB's October 2024 updated enforcement notice states that the agency reserved the right to seek civil penalties against certain controlling parties for violations alleged to occur 90 days after the date the U.S. EPA took final action on California's request for a preemption waiver and authorization.

However, this should not be interpreted as a universal 90-day deadline for every California government fleet to replace its vehicles.

CARB separately states that state and local government fleet requirements do not depend on the federal waiver in the same way. Its current regulatory information continues to identify state and local government fleets as subject to ACF requirements.

For procurement teams, this distinction is critical. A fleet should be assessed according to its ownership, vehicle category, operating circumstances and applicable ACF pathway rather than relying on a generic 90-day countdown.

California Government Fleet Requirements

State and local government agencies have specific ACF obligations.

CARB's current guidance indicates that affected government fleets must report their fleet information through the Truck Regulations Upload and Compliance Reporting System (TRUCRS), with annual reporting for state and local government fleets.

The current ACF framework provides two principal approaches for meeting zero-emission requirements:

• The ZEV Purchase Schedule
• The ZEV Milestones Option

Under the ZEV Milestones Option, fleets progressively increase the percentage of qualifying zero-emission vehicles in their California fleet.

CARB's current milestone schedule includes:

Near-zero-emission vehicles can count similarly to ZEVs through the 2035 model year under the applicable milestone framework.

Because the regulation and proposed amendments continue to evolve, fleet managers should verify the current requirements before making procurement commitments.

What Government Fleet Managers Should Do Now

Rather than treating compliance as a last-minute replacement exercise, government organizations can incorporate ACF requirements directly into their fleet procurement strategy.

1. Audit the Existing Fleet

Create a current inventory covering:

• Vehicle type
• GVWR
• Model year
• Powertrain
• Vehicle use
• California operating location
• Ownership status
• Replacement schedule
• Current ACF reporting status

This creates the baseline for determining which vehicles may require action.

2. Separate Vehicles by Operational Role

Not every vehicle has the same replacement requirements or practical ZEV alternatives.

Separate the fleet into categories such as:

• Vans
• Box trucks
• Pickups
• Work trucks
• Buses
• Tractors
• Specialty vehicles
• Emergency or operational vehicles

This makes it easier to determine which vehicles can transition first and where additional planning is required.

3. Assess ZEV Availability

A government fleet should not select a replacement vehicle based solely on regulatory status.

Consider:

• Required payload
• Range
• Daily mileage
• Charging access
• Vehicle dimensions
• Terrain
• Duty cycle
• Equipment requirements
• Climate and operating conditions
• Maintenance capability

CARB recognizes that vehicle availability can affect compliance and provides mechanisms such as exemptions and extensions in certain circumstances.

4. Plan Procurement Early

Government procurement cycles can be lengthy. Vehicle specifications, budgets, tenders, supplier selection, purchase agreements, delivery and infrastructure planning may all require significant lead time.

CARB's May 2026 guidance provides a vehicle delivery delay extension for qualifying government fleets that entered into a legally binding ZEV purchase agreement at least one year before the applicable compliance date but did not receive the vehicle by January 1 of the compliance year.

That makes procurement documentation especially important.

A fleet should maintain clear records of:

• Purchase agreements
• Vehicle specifications
• Purchase dates
• Delivery commitments
• Supplier correspondence
• Vehicle availability
• Applicable exemptions or extensions

How ACF Changes Fleet Vehicle Procurement

ACF can change how government agencies approach fleet vehicle procurement.

Instead of asking only, "Which truck should we buy?", procurement teams may need to ask:

Which vehicle meets our operational requirement while also supporting our applicable ACF compliance pathway?

That can influence the procurement specification from the beginning.

For example, a municipal agency replacing several work trucks may need to evaluate available zero-emission options alongside payload, range, charging infrastructure, route requirements and equipment compatibility.

The lowest purchase price may not be the best procurement outcome if the vehicle cannot perform its assigned duty cycle.

Building a 90-Day Fleet Upgrade Response Plan

If a government fleet has received a regulatory notice or identified an urgent compliance requirement, a structured 90-day response can help organise procurement activities.

Days 1–30: Assess

• Confirm which ACF requirements apply
• Review the current fleet
• Identify affected vehicles
• Check reporting status
• Categorise vehicles by operational role
• Review available ZEV options
• Identify potential exemptions or extensions

Days 31–60: Source

• Develop vehicle specifications
• Contact qualified suppliers
• Compare available vehicles
• Evaluate charging requirements
• Review commercial terms
• Confirm delivery expectations
• Verify documentation

Days 61–90: Procure and Implement

• Finalise suitable vehicle selections
• Complete procurement approvals
• Execute qualifying purchase agreements where appropriate
• Update fleet records
• Coordinate delivery and infrastructure
• Maintain evidence supporting compliance decisions

This is a procurement planning framework, not a universal legal deadline. Actual compliance dates and requirements depend on the fleet and applicable regulation.

Government Fleet Procurement Should Consider Total Cost

A fleet upgrade should not be evaluated only by vehicle purchase price.

Government organizations should consider:

• Vehicle acquisition cost
• Charging infrastructure
• Energy costs
• Maintenance
• Downtime
• Financing
• Training
• Infrastructure upgrades
• Replacement cycles
• Resale or disposal considerations

CARB identifies incentive opportunities for eligible medium- and heavy-duty zero-emission vehicles subject to ACF requirements. Funding availability and eligibility vary, so agencies should confirm current program conditions before including incentives in procurement budgets.

Common Mistakes During California Fleet Upgrades

Treating the 90-Day Period as a Universal Deadline

The 90-day enforcement language applies to specific circumstances and should not be treated as a blanket replacement deadline for every fleet.

Waiting Until the Deadline to Source Vehicles

Government procurement can take time. Waiting can limit vehicle availability and reduce procurement flexibility.

Choosing Vehicles Without Checking Duty Cycles

A ZEV must still perform the operational job required of it.

Ignoring Charging Infrastructure

Vehicle procurement and infrastructure planning should be coordinated.

Failing to Document Procurement Decisions

Purchase agreements, specifications and delivery records can be important when demonstrating compliance with applicable requirements.

Assuming Every ACF Provision Applies to Every Fleet

ACF requirements differ by fleet category. CARB's current guidance should be checked before making a compliance decision.

How GMTI Can Support Government Fleet Upgrades

California's fleet transition creates a procurement challenge as much as a regulatory one.

Government organizations may need to source vehicles that meet specific operational requirements while coordinating quantities, specifications, driving configuration, availability and international or domestic supply considerations.

GMTI'sSpecialist & Armoured Vehicles service andCommercial Vehicles service are relevant to organizations sourcing specialized and commercial fleet vehicles.

Government and law-enforcement organizations can also explore GMTI'sLaw Enforcement service where specialist fleet requirements apply.

For broader fleet sourcing requirements, GMTI'sCorporate & Fleet Specialist service can be connected naturally to government fleet procurement planning.

Conclusion

California's Advanced Clean Fleets requirements make fleet planning increasingly important for government agencies operating applicable medium- and heavy-duty vehicles.

The 90-day enforcement language should not be interpreted as a universal deadline for every government fleet. The current regulatory position distinguishes state and local government requirements from ACF provisions that depend on federal authorization, while CARB continues to amend and clarify the program.

For government fleet managers, the strongest approach is to assess the existing fleet, confirm applicable requirements, identify replacement priorities, evaluate ZEV availability, plan procurement early, and maintain clear documentation.

For agencies undertaking California fleet upgrades, vehicle procurement should be treated as part of the compliance strategy—not as a separate activity after regulatory decisions have already been made.

Frequently Asked Questions

What is the California Advanced Clean Fleets regulation?

The Advanced Clean Fleets regulation is California's framework for transitioning applicable medium- and heavy-duty fleets toward zero-emission vehicles. Requirements vary according to fleet category, and state and local government fleets remain subject to applicable ACF requirements.

Is there a 90-day deadline for all California government fleets?

No. The 90-day language in CARB's enforcement notice relates to specific enforcement circumstances involving federal authorization. State and local government fleet requirements are treated separately under ACF.

Which government vehicles can be affected by ACF?

CARB states that state and local government agencies with vans, buses and trucks from ¾-ton vehicles through semis with GVWR above 8,500 pounds can be subject to ACF. Specific applicability should be confirmed for the individual fleet.

What is the ZEV Milestones Option?

It is an alternative compliance pathway allowing qualifying state and local government fleets to meet phased ZEV percentages across defined vehicle groups rather than following the ZEV Purchase Schedule.