Washington’s Capital Gains Tax and QSBS: Why Excluded Gain Isn’t Taxed

By Joe Wallin,

Published on Nov 14, 2025   —   1 min read

Updated on November 18, 2025

Washington’s capital gains tax applies only to long-term capital gain recognized for federal purposes. Because QSBS gain excluded under IRC § 1202 is not included in your federal net long-term capital gain, it also drops out of the Washington tax base.

  • Washington’s capital gain base is your federal net long-term capital gain, so Section 1202-excluded QSBS gain is not taxed by the state.
  • The statute and Washington Administrative Code expressly subtract QSBS exclusions when computing Washington capital gains.
  • Only non‑QSBS gains are subject to Washington capital gains tax; maintain documentation to prove QSBS status.
  • To qualify for QSBS, your stock must be issued by a domestic C corporation with assets under $50 million, meet the active business requirement, be acquired at original issuance, and be held for at least five years.
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