Washington Tax Deadlines: Individual & Corporate Filing Guide

Washington Tax Deadlines: Individual & Corporate Filing Guide

Check Washington tax deadlines for individuals and C Corporations. Confirm due dates, extension rules, and exemptions for S Corps and Partnerships.

Washington has no personal or corporate income tax, but imposes a Business & Occupation (B&O) tax.

Washington Tax Deadlines at a Glance (2026)

Entity Type

Filing Requirement

Due Date

Individuals

No filing required

N/A

B&O Tax Return

Quarterly

Apr 30 / Jul 31 / Oct 31 / Jan 31

Businesses

Applies to gross receipts regardless of profitability.

‹ West Virginia Tax Deadlines: Individual & Corporate Filing Guide

Virginia Tax Deadlines: Individual & Corporate Filing Guide ›

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Monitoring Systems

24/7 intrusion detection

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Access Control

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End-to-end Encryption

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Monitoring Systems

24/7 intrusion detection
Quarterly scans & annual pen tests

Access Control

Multi‑Factor Authentication & Role‑based permissions

Regulation Compliant

TLS 256‑bit in transit & at rest
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Customer Stories

Trusted by firms across the board

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Tax Manager

Sama Tributa

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Customer Stories

Trusted by firms across the board

"Research used to be a black hole. Now, I just type the question and get a citable IRS answer in seconds."

Tax Manager

Sama Tributa

"80% faster first drafts. What used to take us two days is now done in two hours."

Managing Partner

Northbridge Tax Advisory