California does not currently charge a mileage tax. The state is running a voluntary pilot program under Senate Bill 339 to test whether a per-mile road usage charge could eventually replace the gas tax, with a final report due to the legislature by December 31, 2026 and the pilot’s statutory authority expiring on January 1, 2027 unless lawmakers extend it.1LegiScan. CA SB 339 2021-2022 Regular Session Chaptered Nothing you drive today is billed by the mile in California.
Why the State Is Testing a Per-Mile Charge
California pays for highway maintenance mostly through the gasoline excise tax, currently 61.2 cents per gallon.2California Department of Tax and Fee Administration. Fuel Taxes That model is losing ground. Cars keep getting more efficient, electric vehicles skip the pump entirely, and revenue is drifting away from what the roads actually cost. The state collected about $7.9 billion in gasoline taxes in the 2024–25 fiscal year, but the per-gallon system ties revenue to fuel burned rather than miles driven.3California Department of Tax and Fee Administration. Gasoline Tax Data
A mileage-based fee changes the basis. You would pay for the distance you drive, not the fuel you use. Someone driving 15,000 miles a year in an electric sedan and someone driving the same distance in a gas pickup would owe the same road charge. That direct link between road use and road funding is the reason state planners keep coming back to the idea.
How the Pilot’s Per-Mile Rate Is Calculated
The SB 339 pilot puts participants into one of two rate groups:1LegiScan. CA SB 339 2021-2022 Regular Session Chaptered
- A flat rate group, where every vehicle pays the same amount per mile regardless of fuel type or fuel economy. The Road Usage Charge Technical Advisory Committee sets this rate.
- An individualized rate group, where each vehicle’s rate equals the state per-gallon fuel tax divided by the EPA’s fuel economy rating for that specific make, model, and year. At the current 61.2-cent gas tax, a car rated at 30 MPG would owe roughly 2.04 cents per mile, and a car rated at 25 MPG would owe about 2.45 cents per mile.
The California Road Charge site currently uses hypothetical rates of 2, 3, and 4 cents per mile for illustration, and notes that any permanent rate would have to be set by the legislature.4California Road Charge. California Road Charge At 3 cents per mile, a driver logging 12,000 miles a year would owe $360 before any credits are applied. The 2017 pilot used a benchmark of 2.8 cents per mile.5California Road Charge. California’s Road Charge Pilot
Credits Prevent Double Charging During the Pilot
The obvious worry with any mileage tax is paying twice, once at the pump and again by the mile. The pilot handles this through a credit system, and the underlying design is revenue neutrality during testing.
For gas-powered vehicles, the program estimates fuel used by combining reported mileage with the vehicle’s EPA fuel economy rating, then credits back the corresponding state gas tax. If a 25-MPG car covers 1,000 miles, the system treats that as roughly 40 gallons of fuel and credits about $24.48 in gas tax (40 gallons × $0.612) against the road charge. Participants only owe the net difference, if any.
Electric vehicle owners get similar treatment. California charges a $121 annual Road Improvement Fee on zero-emission vehicles of model year 2020 and later.6California DMV. Registration Fees Under SB 339, that fee is prorated and credited against the pilot road charge so EV participants aren’t billed for the same road use twice.1LegiScan. CA SB 339 2021-2022 Regular Session Chaptered
Participation is voluntary for non-government vehicles, and the credit rules apply throughout the testing period.
How Mileage Is Reported
The pilot gives participants several options for reporting the miles they drive:4California Road Charge. California Road Charge
- Submitting an odometer photo at set intervals. No hardware, no location data.
- Using a plug-in device that reads total miles from the vehicle’s diagnostic port without recording location.
- Using a plug-in device with GPS, which can distinguish miles on public roads from miles on private property or agricultural land where a road charge wouldn’t apply.
- Using connected vehicle technology in newer cars that transmits mileage data through the vehicle’s own systems.
Privacy Protections
Privacy shaped the pilot from the start. California Vehicle Code Section 3090 directs the Technical Advisory Committee to consider protection of personally identifiable information, the risk of re-identifying location data even after personal details are removed, and the security of each reporting method.7California Legislative Information. California Vehicle Code VEH 3090 The non-GPS options exist because some drivers don’t want the state seeing where they go. Choosing the odometer photo or the plug-in device without GPS lets you participate without sharing travel patterns.
The Existing Flat Fee on Electric Vehicles
Even without a mileage tax, California already charges electric vehicle owners a flat annual fee to partially offset lost gas tax revenue. The Road Improvement Fee under Vehicle Code Section 9250.6 currently runs $121 per year for zero-emission vehicles of model year 2020 and later. It isn’t assessed on the initial registration of a new ZEV bought from a licensed dealer, but applies at renewal.6California DMV. Registration Fees
This flat fee is not a mileage tax. An EV owner who drives 5,000 miles a year pays the same $121 as one who drives 25,000. Part of the pilot’s rationale is that a per-mile system could replace both the gas tax and this flat EV fee with a single charge tied to actual road use.
What Comes After the Pilot
The California Transportation Agency has to deliver its final SB 339 report to the legislature by December 31, 2026, covering whether per-mile revenue collection works at scale, how participants responded to different reporting methods, and what administrative costs look like.1LegiScan. CA SB 339 2021-2022 Regular Session Chaptered The program’s statutory authority expires on January 1, 2027. To keep the program going, expand it, or move to a statewide rollout, lawmakers will need to pass new legislation.
No permanent per-mile rate has been set, and the legislature has not committed to implementing one. The pilot data will show whether the billing infrastructure for millions of individual accounts can operate without eating up more than it collects. That question is what will decide whether California’s road funding eventually shifts from the pump to the odometer, and until it does, drivers in the state continue paying at the gas station or through the flat EV fee, not by the mile.