How to File Washington State Business Taxes: B&O Return in My DOR

To file Washington State business taxes, you register your business with the Department of Revenue (DOR), get a Unified Business Identifier (UBI), and then file a combined excise tax return through the My DOR online portal on the schedule the DOR assigns you. That single return covers your Business and Occupation (B&O) tax on gross receipts along with any state and local sales or use tax you collected. Washington has no corporate or personal income tax, so for most businesses this is the main state filing you’ll make.

What the Combined Excise Tax Return Covers

One return, several taxes. The combined excise tax return reports B&O tax, state sales and use tax, local sales and use tax, and other applicable taxes such as lodging tax.1Washington Department of Revenue. Instructions for Completing the Combined Excise Tax Return

B&O tax is levied on gross receipts rather than net profit, which means you owe it on total revenue before subtracting expenses, payroll, or cost of goods sold.2Washington Department of Revenue. Business and Occupation Tax Virtually every business in the state is subject to it regardless of entity type, including sole proprietors, LLCs, partnerships, and corporations.3Washington Department of Revenue. Business Tax Structure in Washington State

If you sell taxable goods or services, you also collect sales tax from customers and remit it on the same return. The state rate is 6.5%, with local jurisdictions adding their own on top so the combined rate exceeds 10% in some areas.4MRSC. Sales and Use Taxes Use tax covers goods you bought without paying sales tax and then used in Washington, such as equipment from an out-of-state vendor that didn’t charge tax.

Register and Get Your UBI First

You can’t file until you’re registered. Any business conducting activities in Washington needs to register with the DOR and obtain a business license. “Conducting activities” includes selling products, providing services, and even storing inventory in the state. Out-of-state businesses trigger a filing obligation if they have more than $100,000 in combined gross receipts sourced to Washington in the current or prior year, or if they have a physical presence here.5Washington Department of Revenue. Out of State Businesses Reporting Thresholds and Nexus

Skipping registration is expensive. The DOR can impose an additional 5% penalty on all tax owed for the period you operated without a registration certificate.6Washington State Legislature. RCW 82.32.090

Registration starts with the Business License Application, which you can complete online or by mail. The application asks for your legal business name, any trade names, a description of your activities, your start date, your entity type, and your Federal Employer Identification Number or Social Security Number. The processing fee is $50 for a new business, and annual renewals cost $5 in processing fees plus any applicable endorsement fees.7Washington Department of Revenue. Variable Business License Processing Fees You’ll receive a nine-digit UBI number that serves as your tax registration number with the DOR and several other state agencies.8Washington Department of Revenue. Apply for a Business License

You’ll also create a SecureAccess Washington (SAW) account. That’s the login you’ll use for the My DOR portal, where returns, payments, and account updates all live.8Washington Department of Revenue. Apply for a Business License

Filing the Return in My DOR

Electronic filing is the default. All taxpayers must file through My DOR unless the DOR grants a waiver for good cause.9Legal Information Institute. WAC 458-20-22802

After logging in with your SAW credentials, you select the return period and enter gross revenue for each B&O classification that applies to your business. The system calculates the tax owed and applies the small business tax credit if you qualify. For sales tax, you enter total taxable sales and the tax you collected, and the system handles the local rate math based on where each sale occurred. Review the summary, submit, and keep the confirmation number.

File even in a quiet period. If you had zero revenue, you still need to submit a return showing no activity.

Picking the Right B&O Classifications

B&O rates depend on what the business does, and one business can owe under more than one classification if it performs different kinds of activity. The most common rates:

If your business does both retail sales and consulting, you’d report the retail revenue at 0.471% and the consulting revenue at 1.5%. Getting the classification right is one of the areas where mistakes happen most, especially for businesses that blend product sales with services.

Deductions and the Small Business Credit

Because B&O hits gross receipts, deductions can meaningfully cut what you owe. Among those the DOR allows:

  • Interstate and foreign sales: revenue from goods sold and delivered to customers outside Washington can be deducted from your taxable amount.
  • Bad debts: amounts you previously reported as income but later determined uncollectible can be deducted if you’ve also written them off for federal tax purposes.
  • Cash and trade discounts: discount amounts you previously included in gross receipts can be deducted.
  • Incidental investment income: starting January 1, 2026, businesses that are not banking or lending companies can deduct investment income amounting to less than 5% of total worldwide gross income.
12Washington Department of Revenue. Tax Incentives – Deductions

The small business B&O tax credit reduces liability for lower-revenue businesses. Businesses that report at least half of their total B&O taxable amount under service and other activities, real estate brokerage, or contests of chance get a maximum credit of $160 per month ($1,920 annually). All other businesses get a maximum of $55 per month ($660 annually). The credit phases out as income rises, and My DOR calculates it automatically when you file.13Legal Information Institute. WAC 458-20-104

Paying What You Owe

Payment is due at the same time as the return. My DOR accepts:

  • E-check: enter your bank routing and account numbers for a direct withdrawal at no extra cost.
  • Credit or debit card: Visa, Mastercard, American Express, and Discover. A convenience fee applies.14Washington Department of Revenue. Payment Methods
  • Electronic Funds Transfer (EFT): either a direct debit initiated by the DOR or a credit transfer initiated by your bank.

Phone payments are available for excise tax bills. Mailing a paper check is only an option if the DOR has waived your electronic filing requirement.

When Returns Are Due

The DOR assigns your filing frequency based on your estimated tax liability. Three schedules exist:

  • Monthly: due the 25th of the following month. A June return is due July 25.
  • Quarterly: due the last day of the month following the quarter. A first-quarter return (January through March) is due April 30.
  • Annual: due April 15 of the following year.
15Washington Department of Revenue. Filing Frequencies and Due Dates

Your assigned frequency appears in your My DOR account. Newer and lower-revenue businesses typically start on an annual schedule, and the DOR can change your frequency as the business grows. If a due date falls on a weekend or holiday, it moves to the next business day.

Late Filing: Penalties and Interest

Washington’s late-payment penalties escalate quickly. The structure is tiered:

  • By the due date: no penalty.
  • After the due date but within the same month: 9% of the tax owed.
  • More than one month late: 19% of the tax owed.
  • More than two months late: 29% of the tax owed.

The minimum penalty is $5 regardless of the amount owed.6Washington State Legislature. RCW 82.32.090 Interest also accrues on unpaid balances; for the 2026 calendar year, the annual rate on delinquent excise tax is 6%.16Washington Department of Revenue. Interest Rate Tables

The DOR can waive penalties in two situations. First, if the late payment resulted from circumstances genuinely beyond your control, though running low on cash, not knowing you owed taxes, or not receiving the return in the mail generally don’t qualify. Second, if you have a clean 24-month track record of on-time filings and payments, the DOR can waive the penalty on one return within that window even without an extraordinary excuse.17Washington Department of Revenue. Penalty Waivers

Local City B&O Taxes Are Separate

Several Washington cities levy their own B&O taxes in addition to the state tax, including Seattle, Tacoma, Bellevue, and Everett. These local taxes are not reported on your state combined excise tax return and are filed separately with each city.

A portal called FileLocal lets you register, file, and pay local B&O taxes for multiple participating cities in one place. Participating cities currently include Auburn, Bellevue, Des Moines, Everett, Kent, Lake Forest Park, Poulsbo, Renton, Seattle, Shoreline, and Tacoma. You can also file directly with each city by mail or in person.18FileLocal. FileLocal-wa.gov If your business operates in or delivers to customers in any of these cities, check whether you owe local B&O. It’s a common blind spot for businesses that focus only on state-level compliance.

Records to Keep

Washington law requires businesses to keep complete financial records for at least five years, including invoices, receipts, bank statements, and documentation supporting any deductions or credits you claimed.19Washington Department of Revenue. Record Keeping Requirements The DOR can audit up to four years back in most cases, so organized records across that full window protect you if a question comes up. Digital copies alongside paper originals are the simplest insurance against losing documentation to a move or office mishap.