The constitutional challenge to ESSB 6346 is no longer theoretical. The Citizen Action Defense Fund is filing suit against Washington's new 9.9% income tax today — and the legal team they've assembled is serious.
The Legal Dream Team
Former Washington State Attorney General Rob McKenna leads the litigation. Joining him is former Washington State Supreme Court Justice Phil Talmadge — a Democrat who served on the state's high court from 1995 to 2001 and has long argued that a progressive income tax is unconstitutional under Washington law.
CADF Executive Director Jackson Maynard called it "the legal dream team."
Governor Ferguson — who knows McKenna from their time as opposing AG — is reportedly confident he'll prevail. We'll see.
The Core Legal Theory
The argument isn't novel. It's been settled law in Washington since 1933.
Income is property under the Washington State Constitution. Property taxes must be applied uniformly and are capped at 1%. A 9.9% graduated income tax violates both requirements — the uniformity clause and the rate cap under Article VII.
McKenna put it plainly: "Washington's constitution is clear, and the courts have been equally clear for nearly a century — income is property, and progressive income taxes are unconstitutional under existing law."
The Legislature passed ESSB 6346 anyway. Now it's the Supreme Court's problem.
Two Parallel Fights
The CADF lawsuit is one front. The other is the referendum fight — a separate case already before the courts challenging the Legislature's use of the "necessity clause" to block voters from repealing the law by referendum. The Washington Supreme Court takes that up at the end of April.
If the referendum case goes against the state, the Legislature may need a special session. The budget was built around $3 billion in annual revenue that doesn't start flowing until 2029 — which means the stakes are fiscal as well as constitutional.
What This Means Right Now
The law is still on the books. The 2028 effective date still stands. Until a court issues an injunction or strikes the law down, planning matters.
The planning window is open — but so is the litigation. If you're a founder, investor, or high earner in Washington, the right move is to plan as if the tax survives, while tracking the litigation closely.
I'll be covering both cases as they develop.
Questions about your exposure under ESSB 6346? Schedule a call.
