Voters face a tax decision this fall in Tim Eyman’s Initiative 976, which seeks to slash yearly car-tab bills to a flat $30.

Car-tab costs increased after Sound Transit 3, approved by voters in 2016, raised its car-tab tax rate by $80 per $10,000 of vehicle value, to a total $110 per $10,000.

Detractors such as Eyman and state Sen. Steve O’Ban, R-University Place, argue the agency tricked the public into paying excessive car-tab taxes by using a depreciation schedule that inflates car values compared with market-based indexes such as Kelley Blue Book.

Traffic Lab is a Seattle Times project that digs into the region’s thorny transportation issues, spotlights promising approaches to easing gridlock, and helps readers find the best ways to get around. It is funded with the help of community sponsors Madrona Venture Group and PEMCO Mutual Insurance Company. Seattle Times editors and reporters operate independently of our funders and maintain editorial control over Traffic Lab content.

In reality, the depreciation schedule hasn’t changed since 1999. But now that Sound Transit collects higher tax totals, in a lump sum, more people are noticing.

If I-976 prevails, the state would lose $1.9 billion over six years toward highway and ferry maintenance, state troopers, and multimodal projects for transit, pedestrians and bicyclists, the Office of Financial Management (OFM) estimates. Some 62 city and county governments might lose $350 million.

OFM predicts Sound Transit could lose up to $328 million per year. That could mean slower construction of promised light rail to Everett, Ballard and Tacoma.


But it’s debatable whether the agency would take the hit. It defended its car-tab income in court against Eyman’s Initiative 776, a $30 car-tab ballot measure approved by voters in 2002.

For many people, whose cars are more than a couple years old, the Sound Transit sales and property taxes will be higher than the car-tab amounts.

The Seattle Times published an ST3 tax calculator in 2016 as voters decided whether to raise car-tab, sales and property taxes to fund $54 billion in transit expansion. Among other things, the agency aims to complete a 116-mile regional light-rail network and serve roughly 750,000 daily passengers on trains and buses by 2041.

With car-tab taxes back on the ballot, we’ve updated the tax calculator. The new version combines into one total the taxes charged for all three Sound Transit ballot measures since 1996. The total bill provided by this calculator is an estimate. Your actual cost will depend on many factors, especially your personal spending habits.