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What is the hazardous substance tax?

It is a tax on the first possession of hazardous substances in Washington. The Department of Ecology determines which substances are subject to the tax. The tax applies to petroleum products, pesticides, and certain chemicals. There are currently over 8,000 different hazardous substances identified as being subject to the tax.

How do I pay the tax?

The tax is reported on the excise tax return.

What rate do I pay?

The rate is .007 of the wholesale value.

What are the funds used for?

Funds are distributed to the Department of Ecology to help clean up and manage solid and hazardous waste in the state of Washington.

Exemption for Agricultural Protection Products Stored, but Not Used in Washington

Effective September 1, 2015 there is an exemption from the Hazardous Substance Tax for possession of agricultural crop protection products that are warehoused, but not otherwise used or sold in Washington. For more information please see our Special Notice.


Forms & publications

CERCLA list of hazardous substances

FIFRA list of hazardous substances

Tax Reference Manual (pdf)


Revised Code of Washington (RCW) 82.21

Washington Administrative Code (WAC) 458-20-252