2027 Washington Tax Deadlines

Last updated: August 5, 2026

Key Washington tax dates at a glance

• April 18, 2028: Tax-year-2027 Washington capital gains tax return and payment.
• Monthly cycle: Washington excise returns are generally due on the 25th day of the following month.
• Quarterly cycle: Washington excise returns are generally due on the last day of the month following the quarter.
• April 17, 2028: Calendar-year 2027 annual excise return, because April 15, 2028 falls on a Saturday.

Does Washington require a state income tax return for 2027?

Washington does not impose a general personal or corporate net income tax. Tax-year-2027 planning centers on the capital gains tax return due April 18, 2028, and assigned-frequency excise tax returns.

What Washington business deadlines apply for 2027?

Washington business deadlines depend on the tax program, filing frequency, payment method, and state account setup. The state-specific items below should be managed as operational tax work, not as an invented income-tax deadline.

• Washington's capital gains tax applies to allocated long-term capital gains after statutory deductions and exemptions.
• Current law taxes taxable Washington capital gains at 7% after the standard deduction, which is approximately $278,000 and inflation-adjusted.
• Taxable Washington capital gains above the fixed $1 million threshold are subject to the 7% tax plus an additional 2.9%, for a 9.9% rate on amounts over $1 million.
• The $1 million higher-tier threshold is fixed and not indexed; only the tax-year-2027 standard deduction requires Department confirmation.
• Washington does not require quarterly estimated capital gains tax payments under the current annual-return system.
• B and O tax is reported on the excise tax return and is based on gross receipts by classification rather than net income.
• Washington does not have a corporate income tax return or a general Individual income tax return.
• File and pay through Washington My DOR.

When are Washington business estimated payments due?

Washington estimated-payment and payment timing is program-specific. Capital gains tax uses an annual return and payment, while excise tax timing follows the Department-assigned monthly, quarterly, or annual filing frequency.

• April 18, 2028: Washington capital gains tax payment for tax year 2027.
• Monthly excise returns and payments are generally due on the 25th day of the following month.
• Quarterly excise returns are generally due on the last day of the month following the quarter.
• Annual excise returns for calendar-year 2027 are generally due April 17, 2028.

Instead AI helps tax teams treat Washington due dates as operational work, not a static checklist.

Tax-professional context: Washington's tax system is built on gross-receipts and transaction taxes rather than an income tax, so 2027 client work centers on the Business and Occupation (B and O) tax, the capital gains tax, and sales and use tax. The points below cover the compliance mechanics and planning opportunities preparers most often encounter when the usual individual and corporate income-tax filings simply do not apply in Washington.

Filing systems and account setup:

• File and pay B and O, sales/use, and other excise obligations electronically through Washington's My DOR portal (secure.dor.wa.gov).
• The Department assigns each business a monthly, quarterly, or annual filing frequency; confirm each client's assigned frequency before scheduling returns.
• Electronic payment is required or encouraged for most business accounts.

Business and Occupation (B and O) tax planning:

• B and O rates vary by business classification.
• A business with multiple lines of activity may owe B and O under more than one classification simultaneously.
• Classification-specific exemptions, deductions, and credits may reduce the amount due; no filing extensions are available for excise returns.

Sales and use tax considerations:

• Combined state and local sales tax rates vary by jurisdiction.
• Use tax applies to out-of-state and otherwise-untaxed purchases used in Washington.
• Local jurisdictions add to the state rate; special rates apply to certain industries.
• Sales and use returns follow the Department-assigned excise filing frequency.

Capital gains tax planning:

• The 7% capital gains tax is filed on a stand-alone annual return separate from federal filings; coordinate it with the client's federal Schedule D timeline.
• Planning turns on the inflation-adjusted standard deduction and the fixed, non-indexed $1 million higher-tier threshold; confirm the 2027 standard-deduction amount with the Department.

Multi-state and residency planning:

• With no income tax, credits for taxes paid to other states offer limited benefit; residency changes are a recurring topic for clients with mobile income.
• Multi-state businesses should address B and O apportionment/allocation and nexus for gross receipts sourced to Washington.

With Washington's capital gains tax and B and O excise system in place of an income tax, firms can find specialist help through the accounting firm directory.

What sources support these Washington dates?

• Washington capital gains tax.
• Washington capital gains tiered rates.
• Washington filing frequencies and due dates.
• Washington B and O tax overview.

Control Washington capital gains and excise deadlines

Instead's AI-driven tax platform helps Washington teams coordinate business-tax work, payment review, extensions, and filing follow-through before deadlines move from planning to execution.

For Washington practices, integrations, workflows, and businesses help connect research, planning, and operational handoffs without duplicating deadline data. Built for tax professionals who want source-backed state deadline control across clients, entities, and reviewer workflows.