Tax due dates

The date your taxes are due depends on your reporting status. Your reporting status indicates how often you are required to file taxes and is listed on your business license. You can also find it online by accessing your SELF account. If you do not know your reporting status, contact us.

This table summarizes Seattle business license tax due dates for each reporting status:

Reporting statusPeriodTax return due date
Annually Calendar year ends Dec. 31 Jan. 31
Quarterly 1st quarter ends March 31 April 30
2nd quarter ends June 30 July 31
3rd quarter ends Sept. 30 Oct. 31
4th quarter ends Dec. 31 Jan. 31
Monthly March 31, for example Last day of the following month: April 30, for example

Late fees and interest

You pay a penalty fee for filing taxes after the due date. The penalty fee increases the longer you wait to file.

NOTICE: Effective Aug. 1, 2015, penalty rates for late tax payments are increasing. New rates are reflected in the table below. For more information about the penalty increase, see the "About the penalty increase" section below.

Tax return filedLate fee amount ($5 minimum)
1st month after the due date 9% of tax owed (previously 5%)
2nd month after the due date 19% of tax owed (previously 15%)
3rd month after the due date or anytime after 29% of tax owed (previously 25%)

In addition to late fees, you must also pay interest if you file late. Interest accrues from the due date until the date paid. The interest due is equal to:

(interest rate / 360) x (tax owed amount) x (number of days late)

You will not be charged a late fee or interest if you do not owe any tax. But you must still file a tax return.

About the penalty increase

A mandatory change under Senate Bill 6138 requires municipalities to adopt increased penalty rates. Second quarter 2015 tax returns mailed out in late June reflect the old penalty rates. If a business pays an old penalty rate, we will mail a notice for the additional amount due.

If you have any questions, please call our general information hotline at 206-684-8484 or email