The California Energy Commission (CEC) at the end of January announced that sales of zero-emission vehicles (ZEVs) topped 2.5 million in 2025, a trend that shows no signs of slowing down in 2026. During the fourth quarter of 2025 alone, Californians bought 79,066 ZEVs, which represents 18.9% of all new car sales.

Since the end of 2019, new ZEV sales have grown by 300% in California.

In a state that relies on gasoline and diesel tax to build its highways, public transit, and other transportation infrastructure—coupled with its aggressive push to transition to ZEVs—these kinds of data points present a $31 billion problem.

That’s the figure that, over a 10-year period, the California Transportation Commission estimates the state will lose in gas tax revenue through its ongoing efforts to clean the air through cleaner vehicles.

Assembly Bill 1421 (Wilson, D.-Suisun City) looks to address that. It’s a proposal its authors say is nothing more than a “study,” one that started over a decade ago, in 2014, when California passed Senate Bill 1077, authorizing a “Road Usage Charge Technical Advisory Committee” to explore whether the state could replace its gas tax with a mileage-driven tax.

The state completed that pilot in 2017 and at the time, the project proved feasible. Writing in Forbes magazine, attorney and law professor Andrew Leahey said that all the mechanics of the program functioned as expected.

“The report concluded the next step was to simulate revenue flows, identify any system bottlenecks, and resolve challenges to implementation,” Leahey wrote. “That was nearly a decade ago.”

What AB 1421 aims to do now is extend the committee’s lifespan for nine more years, through 2035.

“From the vantagepoint of 2026,” Leahey wrote, “this is no longer a pilot—it’s a weather balloon.”

Moneywise, according to the Assembly Appropriations Committee’s most recent fiscal analysis, the further research will cost taxpayers somewhere in the hundreds of thousands to low millions of dollars.

Despite that, the bill passed its third Assembly reading 43-18 last week.

The passage of AB 1421 has raised concerns. Assemblymember David Tangipa (R.-Fresno), one of the dissenting votes, worries the so-called “study” could translate eventually into a tax, noting the state already has some of the highest fees related to driving in the country.

The gasoline excise tax in California, for example, is over 61 cents per gallon.

In a recent Facebook post, Tangipa argued that AB 1421 is a lot more than “just a study.”

“You’re hearing all of these arguments that a mileage-based tax wasn’t passed last week, it simply was a study,” Tangipa said. “Well it was a study to give us recommendations on how to implement a mileage-based tax.”

During the bill’s debate on the Assembly floor, Assemblymember Carl DeMaio (R.-San Diego) said the true intent of the bill is for a “full-blown mileage tax.”

When you add it all up, DeMaio said, it will cost a family driving two cars approximately $4,200 a year “just for the privilege of driving on crappy roads.”

Wilson disagrees, saying that DeMaio’s assessment mischaracterizes the bill, which she contends would hold California’s electric vehicle drivers accountable to taxes they have been able to avoid by not having to purchase gas.

“AB 1421 asks a basic fairness question,” she said. “How do we ensure all motorists pay their fair share, no more and no less.”

The Ventura County Taxpayers Association, which opposes AB 1421, does agree with that: “Electric vehicle drivers avoid paying the gasoline excise taxes yet enjoy using the same roads internal combustion engine drivers use,” said the VCTA in a statement.

The California Department of Motor Vehicles website, however, indicates that a $121 annual “road improvement fee” applies to 2020 or newer EVs to offset lower gas tax contributions, so it’s not as though ZEV drivers are getting off the hook entirely, just a lot more economically.

Wilson argues that her bill simply asks the California Transportation Commission to “continue studying transportation funding models and to report back to the Legislature with a research-driven analysis that can help guide future decisions,” she said.

Leahey calls this “policy drift,” or what happens when “institutions change not through bold reform, but through inaction in the face of shifting conditions.”

Perhaps most worrisome to just about anybody living in California is the idea of a mileage tax on top of the gas tax. Even though bill authors call the mileage-based model an “alternative to the gas-tax system,” Tangipa disagrees on semantics: an alternative is different from an elimination or replacement.

“There’s no language in the bill right now that repeals the gas tax,” Tangipa argued.

An all-out repeal of the gas excise tax is unlikely, according to the VCTA, who said lawmakers would never eliminate the tax when so many vehicles continue to use gas.

Wilson said she has a plan for that. She said she would specifically direct agencies to find ways to avoid double taxing motorists. She also noted that there will be several local and statewide town halls to ensure commuters, workers, and businesses are heard “before any policy decisions are made.”

In the end, it appears that AB 1421 remains on a slow track to nowhere, according to Leahey.

“AB 1421 is a master class in an ongoing hedge,” he wrote. “It is becoming increasingly likely the committee might qualify for a CalPERS pension before California collects a dime from a real mileage fee.”

AB 1421 passed the Assembly on January 29, 2026, and was read for the first time in the Senate on the same day, where it was referred to the Committee on Rules (RLS) for assignment.

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