Here's the list of exemptions:

• Real estate.

• Interests in a privately-held entity to the extent that the capital gain or loss from such sale or exchange is directly attributable to the real estate owned directly by such entity.

• Assets held in certain retirement accounts.

• Assets subject to condemnation, or sold or exchanged under imminent threat of condemnation.

• Certain livestock related to farming or ranching.

• Assets used in a trade or business to the extent those assets are depreciable under Title 26 U.S.C. Sec. 167(a)(1) of the internal revenue code or qualify for expensing under Title 26 U.S.C. Sec. 179 of the internal revenue code.

• Timber, timberlands, and dividends and distributions from real estate investment trusts derived from gains from the sale or exchange of timber or timberlands. Commercial fishing privileges.

• Goodwill received from the sale of a franchised auto dealership.

See https://dor.wa.gov/taxes-rates/other-taxes/capital-gains-tax