Suppressors are legal in Washington as long as they are registered under the federal National Firearms Act. The state imposes no extra permit, license, or registration beyond the federal process, and RCW 9.41.250 specifically carves out federally registered suppressors from its ban on noise-suppressing devices.1Washington State Legislature. Washington Code 9.41.250 – Dangerous Weapons – Penalty The complication isn’t the suppressor itself. It’s what you attach it to, because Washington’s assault weapon law treats certain suppressor-ready rifles and pistols as banned configurations for new sales.
What Washington Law Requires
RCW 9.41.250 makes it a gross misdemeanor to use any device for suppressing the noise of a firearm unless the suppressor is legally registered and possessed under federal law.1Washington State Legislature. Washington Code 9.41.250 – Dangerous Weapons – Penalty Your federal tax stamp is your entire state-level authorization. There’s no Washington-specific permit, no state registry, and no additional license.
Suppressors can be used for target shooting, home defense, and hunting. Hunting with a suppressor has been legal in Washington since 2011.
How to Buy a Suppressor in Washington
You can’t walk out of a shop with a suppressor the same day you pay for it. The federal transfer process is the gating step, and it looks the same in Washington as it does anywhere else.
Pick a Dealer and a Suppressor
Buy from a dealer who holds a Federal Firearms License with the Special Occupational Tax (often called a Class 3 dealer or SOT). The dealer collects the price of the suppressor plus a transfer fee that varies by shop. The suppressor stays in the dealer’s safe until the ATF approves your paperwork.
File ATF Form 4 and Pay the Tax
The dealer walks you through ATF Form 4, the Application for Tax Paid Transfer and Registration of Firearm. You submit personal information, fingerprint cards, and a passport-style photo, and you pay a one-time $200 federal tax.2Bureau of Alcohol, Tobacco, Firearms and Explosives. National Firearms Act (NFA) Most dealers now file the electronic version (eForm 4), which clears significantly faster than paper.
Wait for Approval
The ATF runs a background check through the FBI. As of February 2026, the average processing time for an eForm 4 filed by an individual was 10 days; trust filings averaged 26 days.3Bureau of Alcohol, Tobacco, Firearms and Explosives. Current Processing Times Those averages shift with application volume, so treat them as a baseline. When your application is approved, the tax stamp goes back to the dealer, who calls you to pick up the suppressor.
Who Can Legally Own One
You need to clear both federal and Washington eligibility rules.
Federally, you must be at least 21, a U.S. citizen or lawful permanent resident, and able to pass an FBI background check. Anyone prohibited from possessing firearms under federal law cannot own a suppressor, including convicted felons, people under domestic violence restraining orders, and unlawful drug users.
Washington adds its own disqualifications under RCW 9.41.040. You cannot possess any firearm, suppressor included, if you have been convicted of a serious offense or any other felony. Convictions for certain misdemeanors and gross misdemeanors also bar possession, including domestic violence offenses, stalking, harassment, and second-degree animal cruelty. Involuntary mental health commitment is a disqualifier unless your rights have been formally restored.4Washington State Legislature. Washington Code 9.41.040 – Unlawful Possession of Firearms – Penalties
The Assault Weapon Problem Every Washington Buyer Needs to Know
This is where Washington suppressor buyers most often run into trouble. The suppressor is legal. The firearm you want to use it with may not be, at least not for a new purchase.
Under RCW 9.41.010, a semiautomatic center-fire rifle with a detachable magazine is defined as an “assault weapon” if it also has a suppressor attached or a threaded barrel designed to accept one. The same rule covers semiautomatic pistols with detachable magazines and threaded barrels capable of accepting a silencer.5Washington State Legislature. Washington Code 9.41.010 – Definitions RCW 9.41.390 then prohibits manufacturing, importing, distributing, and selling any firearm meeting that definition.
The ban targets sale and distribution, not simple possession of firearms you lawfully acquired before the law took effect in 2023. If you already own a threaded-barrel semiauto rifle from before the ban, you can still possess it and run a suppressor on it. But a Washington dealer cannot sell you a new semiautomatic center-fire rifle with a detachable magazine and a threaded barrel. New buyers shopping for a suppressor host should look at bolt-action rifles, lever-action rifles, rimfire semiautomatic rifles, or shotguns. None of those fall under the assault weapon definition.
Filing as an Individual vs. Using a Trust
If you register the suppressor to yourself, you are the only person who can legally possess it. Nobody else in your household can use it, transport it, or have access to it unless you are present.
An NFA trust is a legal entity that owns the suppressor in your place. The trust names trustees, who are authorized to possess and use its property, and beneficiaries, who inherit it. Multiple trustees can access the suppressor independently, which is the main practical reason people choose this route. If one trustee dies, the trust keeps owning the item without a new transfer.
The tradeoff: every trustee counts as a “responsible person” under ATF rules and has to submit photos, fingerprints, and a background check whenever an NFA item is added. Trust applications also average longer processing times than individual filings. The trust needs language specifically authorizing NFA ownership, and every trustee must be legally eligible to possess firearms under both federal and Washington law.
Penalties for Getting It Wrong
Owning or using an unregistered suppressor carries consequences at both levels of government, and the federal exposure is the serious one.
Under Washington law, using a suppressor that isn’t federally registered is a gross misdemeanor under RCW 9.41.250, punishable by up to 364 days in county jail and a fine of up to $5,000.6Washington State Legislature. Washington Code 9A.20 – Classification of Crimes Violating the assault weapon sale and distribution ban under RCW 9.41.390 is also a gross misdemeanor with the same maximum.
Federally, possessing an unregistered NFA firearm is a felony under 26 U.S.C. 5871, carrying up to 10 years in federal prison and a fine of up to $10,000.7Office of the Law Revision Counsel. 26 USC 5871 – Penalties There is no mechanism to retroactively register a suppressor that was never registered to begin with.2Bureau of Alcohol, Tobacco, Firearms and Explosives. National Firearms Act (NFA)
Taking a Suppressor Across State Lines
Federal law requires ATF pre-approval on Form 5320.20 to transport certain NFA items across state lines, but suppressors are not on that list. The requirement covers machine guns, short-barreled rifles, short-barreled shotguns, and destructive devices.8Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts You can take a registered suppressor out of Washington without filing anything extra, provided the destination state allows them. A handful of states ban suppressors outright, and arriving in one of those states with a lawfully registered Washington suppressor is a serious criminal offense regardless of your federal tax stamp. Check the law of every state on your route before you travel.