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Today, May 1, 2026, marks the final finalized deadline for Washington State residents to file their 2025 Capital Gains Excise Tax returns and remit any owed payments. This date serves as an essential extension of the typical April 15 deadline, providing necessary relief for taxpayers navigating the first year of the state’s new tiered tax structure.
The Reason for the Extension
The extension was triggered by IRS disaster relief granted to residents in several Washington counties following severe winter storms, straight-line winds, and flooding that began in December 2025. To maintain administrative consistency, the Washington Department of Revenue (DOR) aligned the state’s capital gains filing and payment deadline with the IRS’s May 1st relief date.
The 2025 Tiered Rate Structure
Tax year 2025 introduces a significant shift in how the tax is calculated. While the tax originally launched as a flat 7% rate, it is now a two-tier system:
- 7% Rate: Applies to net long-term capital gains above the standard inflation-adjusted deduction (set at $278,000 for the 2025 tax year).
- 9.9% Rate: Applies to net long-term capital gains exceeding $1 million.
Who Is Affected?
- Individual Taxpayers: The tax applies to individuals selling long-term assets such as stocks, bonds, and business interests.
- Pass-Through Entities: While corporations are exempt, individuals who receive capital gain allocations from pass-through entities (S-corps, LLCs, Partnerships) are liable for the tax on their personal portion.
- Exemptions: Real estate, retirement accounts, and certain small family-owned businesses remain exempt from this excise tax.
Consequences of Missing Today’s Deadline
As this is a finalized extension, any returns filed or payments submitted after 11:59 PM tonight will be subject to standard penalties and interest:
- Late Filing Penalty: Up to 25% of the tax due.
- Late Payment Penalty: Starts at 9% and can increase to 29% depending on the length of the delay.
- Interest: Accrues daily on any unpaid balance starting May 2, 2026.
