Washington State House of Representatives Pass Income Tax Bill

Overnight Debate over SB 6346.

The overnight, record-setting 24-hour debate ends. The Washington State House of Representatives officially passed a controversial income tax bill (SB 6346) Tuesday dubbed the “millionaire’s tax” 52 to 46.

The proposed bill imposes a 9.9% tax on high-income earners, earning more than $1 million annually, applying only to earnings above that threshold. Amendments that would limit it to the $1 million threshold were rejected, paving the way for the limit to be reduced in the future.

The proposal now heads to the state Senate for confirmation before going to the governor’s desk for approval. It must be confirmed by the Senate by March 12th, 2026. If passed, the tax is slated to take effect in 2028.

Adding an income tax in Washington has been widely unpopular with residents. Washington State voters have rejected proposed state income taxes 11 times over the past century. Washington is one of nine states that has no income tax. The other states are Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas and Wyoming.

Governor Bob Ferguson has already confirmed he will sign the bill into law. You can read more about the details and the process of the bill here.

It is highly likely the bill will be legally challenged if passed. The primary argument against it constitutionally is that the Washington State Constitution requires property taxes to be uniform and this tax only applies to income over $1 million. A 1933 state Supreme Court ruling (Culliton v. Chase) held that income is property and must be taxed uniformly, which historically has blocked graduated income taxes.

The bill includes a clause that prevents it from being referred to voters, forcing opponents to use a full initiative to challenge it.

Proponents of the bill hope the court will define this as an excise tax (a tax on the transaction of earning) instead of a property tax, echoing the recent approval of the state’s capital gains tax.