Washington law defines "untraceable firearms" as any firearm manufactured after July 1, 2019, that is not an antique firearm and that cannot be traced by law enforcement by means of a serial number affixed to the firearm by a federally licensed manufacturer or importer.  RCW 9.41.010(35).
 
Washington prohibits the manufacture of an untraceable firearm with intent to sell.  A violation of this restriction is punishable as a class C felony.  RCW 9.41.190(1)(d), (5).
 
Washington further prohibits knowingly or recklessly allowing, facilitating, aiding, or abetting the manufacture or assembly of an undetectable firearm or untraceable firearm by a person who:  (a) is ineligible under state or federal law to possess a firearm; or (b) has signed a valid voluntary waiver of firearm rights that has not been revoked.  Failure to conduct a background check is prima facie evidence of recklessness.  A violation of this restriction is punishable as a gross misdemeanor for a first offense, or as a class C felony for a repeat offense.  RCW 9.41.325.

Untraceable Firearms—General Limitations.
 
The definition of "untraceable firearm" is revised to mean any firearm manufactured after July 1, 2019, that is not an antique firearm and that cannot be traced by law enforcement by means of a serial number affixed to the firearm by a federal firearms manufacturer, federal firearms importer, or federal firearms dealer in compliance with all federal laws and regulations.
 
After June 30, 2022, manufacturing, causing to be manufactured, assembling, causing to be assembled, selling, offering to sell, transferring, or purchasing an untraceable firearm is prohibited.
 
After September 10, 2022, knowingly or recklessly possessing, transporting, or receiving an untraceable firearm is prohibited, with exceptions for law enforcement agencies and federally licensed firearms importers, manufactures, and dealers.
 
The foregoing restrictions on selling, offering to sell, transferring, purchasing, possessing, transporting, or receiving untraceable firearms do not apply to firearms rendered permanently inoperable, or that are antiques, or were manufactured prior to 1968.
 
A violation of these restrictions in the first instance is a civil infraction punishable by a monetary penalty of $500.  A second violation is punishable as a misdemeanor.  A third or subsequent violation is punishable as a gross misdemeanor.  Additionally, any violation of these restrictions with three or more untraceable firearms at a time is punishable as a gross misdemeanor. 
 
Untraceable Firearms—Construction with Intent to Sell.
 
After July 1, 2022, the prohibition on manufacturing an untraceable firearm with intent to sell is expanded to also prohibit a person from causing to be manufactured, assembling, or causing to be assembled an untraceable firearm with intent to sell.  Violations of this restriction are punishable as a class C felony.
 
Unfinished Frames and Receivers.

A "frame or receiver" is defined as a part of a firearm that, when the complete firearm is assembled, is visible from the exterior and provides housing or a structure designed to hold or integrate one or more fire control components, even if pins or other attachments are required to connect the fire control components.  Any such part identified with a serial number is presumed to be a frame or receiver, absent an official determination by the Bureau of Alcohol, Tobacco, Firearms, and Explosives or other reliable evidence to the contrary.  "Fire control component" means a component necessary for the firearm to initiate, complete, or continue the firing sequence, including any of the following:  hammer, bolt, bolt carrier, breechblock, cylinder, trigger mechanism, firing pin, striker, or slide rails.
 
An "unfinished frame or receiver" is defined as a frame or receiver that is partially complete, disassembled, or inoperable, that:  (i) has reached a stage in manufacture where it may readily be completed, assembled, converted, or restored to a functional state; or (ii) is marketed or sold to the public to become or be used as the frame or receiver of a functional firearm once finished or completed.  "Readily" means a process that is fairly or reasonably efficient, quick, and easy, but not necessarily the most efficient, speedy, or easy process.  "Partially complete," as it modifies frame or receiver, means a forging, casting, printing, extrusion, machined body, or similar article that has reached a stage in manufacture where it is clearly identifiable as an unfinished component part of a firearm.
 
After June 30, 2022, selling, offering to sell, transferring, or purchasing an unfinished frame or receiver is prohibited, with exceptions for purchases by federally licensed firearms importers, manufacturers, or dealers.
 
After September 10, 2022, knowingly or recklessly possessing, transporting, or receiving an unfinished frame or receiver is prohibited, with exceptions for federally licensed firearms importers, manufacturers, or dealers.
 
The restrictions applicable to unfinished frames and receivers do not apply to unfinished frames or receivers that have been imprinted with a serial number issued by a federally licensed firearms importer, manufacturer, or dealer.
 
A violation of these restrictions in the first instance is a civil infraction punishable by a monetary penalty of $500.  A second violation is punishable as a misdemeanor.  A third or subsequent violation is punishable as a gross misdemeanor.  Additionally, any violation of these restrictions with three or more unfinished frames or receivers at a time is punishable as a gross misdemeanor.