The multiple tax bills adopted by the Legislature last year collectively represented the largest tax increase going back over 30 years. For this analysis, I reviewed fiscal notes and legislative budget notes. Digital legislative and fiscal records are spotty prior to the 2000s, but some information is available online going back to the early 1990s. I compared the estimated fiscal impact of each tax bill based on the revenues expected at the time of enactment for the first biennium in which the tax was to be fully implemented. I adjusted the revenue impacts for inflation.

I’ve updated the list of largest individual tax increases to include the tax bills adopted this year. Three bills make the list of the top 40 tax increases. (Note that not all the fiscal notes are final, so this could change.)

The net impact of ESSB 6346, which imposes an income tax and reduces some sales taxes and business and occupation taxes, makes it the largest tax increase going back at least to the early 1990s. (For more on the income tax, see here and here.)

This analysis reflects what was known at the time of enactment, so a tax may show up on the list even if it was later reduced or repealed. For example, 2026 legislation repealed the 2025 estate tax increases, but the list still includes the 2025 bill’s original fiscal estimate.