The tiered rate
From tax year 2025, the first $1 million of taxable Washington capital gains is taxed at 7%, and gains above that at 7% plus an additional 2.9%. The change first hits the 2025 return.
Washington Tax Changes 2026: Capital Gains Tiers | HelloBooks Washington’s capital gains tax now has a 9.9% tier above $1 million from 2025, and 2025 returns and payments were due May 1, 2026.
Washington · capital gains excise tax
Washington’s capital gains tax gets a second tier
Washington has no wage income tax, but clients with large long-term gains file the state capital gains return, and both the rate and the 2025 due date changed.
Free Plan with invoices within 200 transactions, bills & quotes — no credit card.
Rate above $1 million
9.9%
- Rate on first $1 million
- 7%
- 2025 return and payment due
- May 1, 2026
- Extended filing deadline
- October 15, 2026
Applies: Tax year 2025 onwardFrom IRS.gov · checked October 10, 2026
The 2025 due date
After the IRS postponed deadlines for the December 2025 storms and flooding, the DOR moved 2025 capital gains returns and payments to May 1, 2026. A state extension needs a federal extension too, and it extends filing to October 15, 2026 but not payment.
FAQ
Frequently asked questions
- Does the May 1 date apply to 2026 returns too?
- No. The DOR moved the date for the 2025 filing year only.
Sources
General information for tax professionals, not advice on a specific return. Figures are from IRS.gov on the date shown; check the current IRS instructions before filing.
Start automating your books today
Free Plan with full access to the AI accountant — no credit card, no time limit.