What’s next for the Millionaire’s Tax?

The 2026 Legislative Session ended with a huge victory for progressive revenue after the passage of SB 6346: The Millionaire’s Tax. Once collection starts in 2029, this tax – which will apply to less than 1% of households in Washington – is projected to bring in over $3 billion annually. That revenue will support Washington schools, including free school meals for all students, as well as critical programs like SNAP and Medicaid. It’s also paired with significant tax relief for the 99% of Washingtonians who will not pay the tax – including eliminating sales tax on over-the-counter medications, diapers and hygiene products, cutting B&O taxes for small businesses, and massively expanding access to the Working Families Tax Credit. Overall, this bill addresses Washington’s upside-down tax code by cutting taxes for those who are unfairly burdened and asking the ultra-wealthy to contribute their fair share.

However, the ultra-wealthy are pouring resources into preventing this bill from progressing. Multiple challenges are expected to arise in the coming years before the tax goes into effect in 2029. Here’s what we know is coming, and what you can do to make your voice heard:

A ballot fight

Multi-millionaire Brian Heywood from California is no stranger to pushing ballot measures in Washington State. Last year he funded four initiatives aimed at repealing climate progress and funding for early learning and long-term care. His organization, Let’s Go Washington, has already filed a referendum to overturn the Millionaire’s Tax and is aiming to start gathering signatures soon.

It’s likely that we’ll see the Millionaire’s Tax come up on the ballot this November, and that there will be significant advertising beforehand from both supporters and opposition to the bill.

Supreme Court Challenges

Legal challenges have also already begun. In early April, opponents of the bill filed to overturn it, calling a tax on millionaires unconstitutional. The legal opposition is being led by Citizen Action Defense Fund, with former state Attorney General Rob McKenna acting as the lead attorney.

These court battles will start at lower courts but will almost certainly end up before the Washington State Supreme Court. Supporters expect lower courts to side with the opponents in alignment with prior rulings from the Supreme Court but are confident in the constitutionality of the Millionaire’s Tax.

The Millionaire’s Tax is a huge step for Washington’s tax code and economic justice, but we’ll have to fight to protect that progress. By creating a fair, progressive tax code, our legislature can fund the programs that Washingtonians rely on by leveraging the prosperity that our state supports.