State Set to Track Your Miles – What You Might Pay

White SUV driving on a sunny road — Photo: Jenson / Shutterstock

California transportation officials have spent over a year testing how to charge drivers by the mile instead of by the gallon, and the research could shape how every Californian pays for roads within the next decade.

Quick Take

Caltrans ran a Road Charge Collection Pilot from August 2024 through January 2025 to test per-mile fee collection methods
Assembly Bill 1421 would extend state research and require a formal report to lawmakers by January 1, 2027
No statewide mileage tax rate, start date, or payment rule currently exists in law
Gubernatorial candidates have turned the research program into a 2026 campaign flashpoint

What California Actually Tested

The California Road Charge Collection Pilot was not a tax. It was a controlled study. Caltrans and the California Transportation Commission wanted to know if a per-mile fee could fairly and reliably replace the state gas tax as more drivers switch to electric and hybrid cars. The pilot grew out of Senate Bill 339 and built on an earlier research effort authorized by Senate Bill 1077.

Volunteers in the pilot paid under two different methods. One group paid a flat fee for every mile driven. A second group paid a fee tied to their specific vehicle, calculated by dividing the state’s per-gallon gas tax by that vehicle’s official fuel-economy rating. Comparing these two approaches lets planners judge which system treats drivers more fairly across different cars and driving habits.

The final pilot report is not due to the Legislature until December 2026. Until it lands, lawmakers do not have the hard data on cost, accuracy, or public acceptance that any serious statewide program would need before moving forward.

The Bill Driving the Current Debate

Assembly Member Lori Wilson introduced Assembly Bill 1421 on February 21, 2025. The bill does not create a mileage tax. It requires the state to consolidate existing research and recommendations on road-user charges and report findings to legislative committees by January 1, 2027. It also references California’s existing Road Usage Charge Technical Advisory Committee, a group already working on this exact question.

In plain terms, Assembly Bill 1421 asks the state to organize its homework and turn it in by a deadline. It does not set a per-mile rate. It does not create a collection system. It does not require any driver to pay anything. The bill text simply does not go that far.

Why the Gas Tax Is Losing Ground

The underlying problem is real and growing. Gas tax revenue depends on how much fuel people burn, and that amount keeps shrinking. Electric vehicles pay no fuel tax at all, and hybrids pay far less than older gas-only cars did. The Congressional Budget Office has flagged this same structural problem on the federal level, warning that the Highway Trust Fund faces mounting pressure as fuel efficiency rises nationwide.

Four other states, Utah, Oregon, Virginia, and Hawaii, have already tried road usage charging systems, and those efforts have struggled to scale up to full replacement programs. That track record matters. It suggests that even if California finishes its research cleanly, turning a pilot into a working statewide system is a much harder and slower task than announcing one.

Politics Has Outpaced the Policy

California’s governor’s race has turned this technical research program into a loud campaign issue. Candidate Xavier Becerra said “everything should be on the table” when discussing road funding options, while his campaign separately stated he has not proposed a mileage tax. That is a meaningful distinction. Being open to studying an idea is not the same as pushing to enact it, and conflating the two does voters no favors.

@XavierBecerra
You said that California needs the money for road repairs, the current gas tax is about $37 million a day, what did you do with the money.
No mileage tax.
NO NEW TAXES pic.twitter.com/3izyRzBVwz

— B Rad (@jsbees) October 31, 2026

Opponents, including candidate Steve Hilton, have seized on the issue, and that reaction tracks with how Californians already feel about driving costs. The state already carries some of the highest gas taxes and vehicle registration fees in the country. Layering political uncertainty about a possible new per-mile charge onto that existing frustration is a predictable recipe for backlash, regardless of how the final policy gets designed.

What Comes Next

Two deadlines will determine where this goes. The pilot’s final report is due by December 2026, and Assembly Bill 1421’s consolidated report to lawmakers is due by January 1, 2027. Those documents should finally answer the open questions: what a fair rate looks like, how privacy and location data would be protected, and whether a mileage charge would replace the gas tax or simply stack on top of it. Until then, drivers are watching a research program, not a new bill at the pump.