Washington State Income Tax: The Complete Guide

Key Takeaways

• Washington capital gains tax: 7% up to $1M, 9.9% above.
• New individual income tax: 9.9% on income over $1M, effective 2028.
• QSBS gains remain exempt under Washington's capital gains tax.
• Pass‑through entities can elect entity‑level tax for the new income tax.
• Ongoing constitutional challenge could delay or overturn the 2028 tax.

Pulse Analysis

Washington’s tax landscape is undergoing a seismic shift that founders and investors can’t ignore. While the state never imposed a broad wage tax, it introduced a capital‑gains excise tax in 2021, taxing long‑term gains at 7% up to $1 million and 9.9% beyond that. The regime respects the federal Section 1202 exclusion, allowing qualified small‑business stock (QSBS) gains to remain untaxed—a distinct advantage over California, where capital gains are ordinary income. For entrepreneurs planning liquidity events, the timing of asset sales, entity structure, and even trust arrangements now carry state‑level tax consequences.

The upcoming individual income tax, slated for Jan 1, 2028, adds another layer of complexity. A flat 9.9% rate applies to any Washington‑taxable income above a $1 million standard deduction, using federal AGI as the base. This means traditional retirement distributions, pensions, and even 401(k) withdrawals count toward the threshold, while Roth withdrawals do not. High‑net‑worth retirees and dual‑earner households must reassess residency and retirement‑income strategies, as the tax could bite at income levels previously considered safe.

Legal uncertainty looms, with a constitutional challenge filed in Klickitat County alleging a violation of the uniformity clause. Although the Washington Supreme Court rejected a referendum challenge, the pending litigation could delay or reshape the 2028 rollout. Meanwhile, businesses can mitigate exposure by electing a pass‑through entity‑level tax for S‑corps and LLCs, and by leveraging QSBS exclusions and 1045 rollovers. Early planning—spanning entity selection, timing of exits, and trust design—is essential to preserve the tax advantage that once made Washington a magnet for tech talent and capital.