April 2026: The Home Stretch and Washington’s New Tax Safe Harbors

If you feel like the goalposts for Washington business owners keep moving, you aren’t imagining it. As we head into April, we are officially in the “home stretch” of the most complex tax season in recent memory.

While the mid-March deadlines for S-Corps and Partnerships are now in the rearview mirror, the real work is just beginning for many of you. Between the final passage of the state’s 9.9% “Millionaires’ Tax” and the fast-approaching April 30th deadline for the new Seattle B&O rules, there is a lot to unpack. This month, I’m cutting through the noise to show you how these legislative shifts impact your 2026 strategy and, ultimately, your business’s market value.

The “Millionaires’ Tax” is Now Law: What’s the Fallout?

The headline-grabbing Washington State Wealth Tax (often called the Millionaires’ Tax) passed the legislature in mid-March and is headed for the Governor’s desk.

• The Big Number: A 9.9% tax on household earnings over $1 million.
• The Small Business Win: To pass this bill, the state included significant B&O tax credits and expanded exemptions for small firms to offset the cost of living.
• Broker’s Perspective: If you are planning an exit, don’t panic. The law carries over the same exemptions as our Capital Gains tax—meaning the sale of a qualified family-owned small business is generally exempt. Your “nest egg” from a future sale remains protected. Check my guide on selling a business in Washington for more on these exemptions.

Seattle B&O: The April 30th Countdown

If your business operates in Seattle, mark your calendar for April 30, 2026. This is the first filing deadline under the new “Seattle Shield” rules.

• The $2 Million Safe Harbor: If your Seattle gross receipts are under $2 million, you likely owe $0 in city B&O tax this year.
• Don’t Make This Mistake: Even if you owe zero, you are still required to file. * Why it matters: During business exit planning, I often see “no-tax-due” filings missed. When a buyer does due diligence, these missing filings appear as “unresolved liabilities” and can stall a sale. Keep your record clean!

Service Tax Expansion: Are You Collecting?

Since the start of the year, Washington has expanded Retail Sales Tax to services that were previously exempt. If you haven’t updated your invoicing yet, April is the time to audit your Q1 books.

• Newly Taxable Services: IT support, ad design, custom web development, and temporary staffing.
• The “Penalty Relief” Window: The Department of Revenue has a temporary program to waive penalties. If you realized you missed Q1 collections, now is the time to self-correct before the state catches it. Maintaining a profitable and compliant business is key to a high valuation.

April 15th: The Final Federal Deadline

For C-Corps, Sole Proprietors (Schedule C), and Single-Member LLCs, the clock is ticking.

• Estimated Payments: April 15 is also the due date for Q1 2026 Federal estimated payments.
• The AI Edge: I’m seeing a massive trend of owners using AI-integrated bookkeeping tools to slash the time it takes to prep for this deadline. Companies that leverage tech to lower their “administrative burden” are currently seeing higher valuation multiples because they are leaner and more profitable.

Key Deadlines for April 2026

Is your business “Market Ready” this Spring? With the new tax credits and service tax rules changing the math on your profitability, your business’s value has likely shifted since last year.

Ready to see where you stand? Visit Grace Chang Business Broker for a confidential business valuation today.