What Are NFA Firearms? Categories, Costs, and Penalties

NFA firearms are the weapons and accessories regulated under the National Firearms Act of 1934, a federal law that requires each item be individually registered with the Bureau of Alcohol, Tobacco, Firearms and Explosives, approved in advance, and in some cases taxed before anyone can legally possess it. Six categories fall under the statute, ranging from suppressors to machine guns, and the rules shifted meaningfully on January 1, 2026, when Congress zeroed out the $200 tax on most categories but kept it in place for machine guns and destructive devices. Getting any part of this wrong is a federal felony, so the details matter.

The Six Categories

Federal law lists eight specific items that qualify as “firearms” under the NFA, which practitioners group into six categories.¹

Machine guns. Any weapon that fires more than one shot with a single trigger pull without manual reloading. The definition also covers the frame or receiver of such a weapon, conversion parts, and any combination of parts that could be assembled into one.¹
Silencers (suppressors). Any device that reduces the sound of a gunshot, plus component parts intended for building one.
Short-barreled rifles (SBRs). A rifle with a barrel under 16 inches, or any weapon made from a rifle with an overall length under 26 inches.²
Short-barreled shotguns (SBSs). A shotgun with a barrel under 18 inches, or any weapon made from a shotgun with an overall length under 26 inches.²
Destructive devices. Bombs, grenades, rockets, mines, and similar explosive or incendiary items, plus any firearm with a bore diameter over one-half inch. Standard shotguns recognized as suitable for sporting purposes are specifically excluded.³
Any Other Weapons (AOWs). A catch-all for concealable firing devices, including smooth-bore pistols made to fire shotgun shells, disguised firearms like pen guns and cane guns, and weapons with combination shotgun-and-rifle barrels between 12 and 18 inches.²

The barrel and length numbers are hard lines. A 16-inch rifle barrel is a standard firearm; at 15.9 inches, the same weapon is an unregistered NFA item and a felony. Modifying a firearm without measuring carefully, or without understanding how the ATF measures barrel length, is one of the most common ways people fall into a violation without meaning to.

The 1986 Cutoff on Machine Guns

Machine guns carry a restriction that overrides everything else in this article. The Firearm Owners’ Protection Act of 1986 made it illegal for civilians to possess or transfer any machine gun that was not already lawfully registered before May 19, 1986.⁴ The only exceptions are transfers to government agencies and items already in the registry before that cutoff.⁵

No amount of paperwork works around this. If a machine gun was not registered by May 1986, a civilian cannot own it. The pool of transferable guns is fixed and shrinks over time as items are damaged, seized, or destroyed.

What You Pay in 2026

The most important recent change to NFA ownership took effect January 1, 2026, when a provision of the One Big Beautiful Bill Act eliminated the transfer and making tax on most categories. For decades every NFA transaction required a $200 tax stamp. That is no longer true for most items.⁶

Machine guns and destructive devices still carry a $200 tax on transfers and new manufacturing.⁷
Silencers, SBRs, SBSs, and AOWs now have a $0 transfer and making tax.⁶

Nothing else changed. Registration, background checks, and paperwork all still apply. Older guides that reference a $200 stamp for a suppressor or a $5 transfer for an AOW are out of date.

Three Ways to Register, and Who Can Touch the Item

An NFA firearm can be registered to an individual, to a trust, or to an entity like a corporation or LLC. The choice affects who may legally possess the item and what happens when you die.

Individual registration. The item is registered in your name alone, and you are the only person who may possess it. No one else may have unsupervised access, not a spouse and not a range partner. You submit fingerprints and a photograph with the application.⁸
Trust registration. A gun trust holds title. Any trustee named in the trust (a “responsible person”) may possess the item without the original owner present. Every responsible person submits fingerprints and a photograph with the application.⁹
Entity registration. A corporation or LLC holds title, with designated officers possessing items on the entity’s behalf. Every responsible person within the entity submits fingerprints and photographs.

Trusts were once popular partly because they let applicants skip the fingerprint and photograph requirements. That gap closed in 2016. The remaining advantages of a trust are shared access among named trustees and a smoother inheritance path, since successor trustees can take possession without waiting on probate.

Whoever is not on the registration has no right to possess the item. A registered individual owner whose roommate has the safe combination is exposing that roommate to a constructive possession charge. The same reasoning covers loose parts: courts have found that owning every component needed to build an unregistered NFA firearm, even stored separately, can establish possession of the illegal weapon when there is no lawful reason to have the parts in that combination.

Federal approval also does not override state law. Roughly eight states and the District of Columbia prohibit civilian possession of suppressors entirely. Several states ban SBRs or SBSs, and machine gun rules vary widely from state to state. Check your state’s law before filing anything with the ATF, because an approved tax stamp is worthless if the item itself is illegal where you live.

How the Application Works

Every NFA transaction requires ATF approval before you take possession. Two forms cover most private transactions:

ATF Form 4 (5320.4) is used when a licensed dealer transfers an existing NFA firearm to you.¹⁰
ATF Form 1 (5320.1) is used when you want to make and register a new NFA firearm yourself, such as building an SBR from a pistol lower.¹¹

Both forms ask for detailed applicant information and the firearm’s manufacturer, model, caliber, and serial number. Individual applicants include two FD-258 fingerprint cards and a photograph.⁸ Trust and entity applicants have every responsible person complete ATF Form 5320.23 with fingerprints and a 2×2-inch frontal photograph taken within a year of filing.⁹

Before submitting, every applicant and responsible person sends a copy of the application (or the 5320.23) to the chief law enforcement officer for their area, typically the local chief of police, county sheriff, or district attorney.¹² The CLEO has no authority to approve or veto; the notification is informational.

Applications go to the ATF’s NFA Division in Martinsburg, West Virginia, by mail or through the ATF’s electronic eForms portal.¹⁰ Electronic filing is faster at every step. The ATF runs an FBI background check on each applicant, and you cannot possess the item while the application is pending. Once approved, the ATF issues a tax stamp (physical for paper submissions, digital for eForms). Keep a copy accessible whenever the item leaves your home.

As of early 2026, eForms Form 4 approvals for individual applicants have run around 4 days at the median, while trust-based eForms Form 4 applications run around 24 days. Paper filings still take months. These times fluctuate with volume.

Traveling Across State Lines

Interstate travel with certain NFA items requires advance written approval from the ATF. Machine guns, SBRs, SBSs, and destructive devices all fall under this rule. You file ATF Form 5320.20 with the dates and locations of your travel and cannot move the item until the ATF approves.¹³ The approval is time-limited; travel beyond the approved window requires a new application.

Silencers and AOWs do not require Form 5320.20 approval for interstate travel. State law still applies, though. Carrying a suppressor into a state that bans them is a state crime regardless of federal paperwork.

If you ship an NFA item interstate through a common carrier, provide the carrier with a copy of the approved Form 5320.20, which they keep for the duration of the shipment.¹³

Passing an NFA Item to an Heir

When a registered owner dies, the item transfers to an heir or estate beneficiary without any transfer tax, even for machine guns and destructive devices that would otherwise cost $200.¹⁴ The executor files ATF Form 5, a tax-exempt transfer application, to put the item in the heir’s name. The heir must still pass a background check and be legally eligible to possess firearms.

This is where trusts show their value most clearly. A properly drafted gun trust names successor trustees who can take immediate possession, avoiding a limbo where no one is legally authorized to handle the items during probate. Without a trust, an unauthorized person taking possession of an estate’s NFA items, even briefly, risks a federal charge. Executors who are unsure should contact the NFA Division directly rather than guess.

What a Violation Costs

Any violation of the NFA (possessing an unregistered item, failing to pay a required tax, transferring without approval) is a federal felony. The statute itself sets a maximum penalty of a $10,000 fine and ten years in prison.¹⁵ The general federal sentencing statute allows fines up to $250,000 for any felony, which courts can apply on top of the NFA-specific cap.¹⁶

These are not penalties reserved for arms dealers. People have been convicted for shortening a rifle barrel without registering the result, for possessing auto sears bought at a gun show, and for building suppressors from kits ordered online. The ATF does not draw a sharp line between accidental and intentional violations at the charging stage. If the item exists and it is not registered, the problem is already on you. The only reliable defense is knowing what falls under the NFA and finishing the paperwork before taking possession.

1
Office of the Law Revision Counsel. 26 U.S. Code 5845 – Definitions
2
Bureau of Alcohol, Tobacco, Firearms and Explosives. ATF National Firearms Act Handbook – Section: 2.1 Types of NFA Firearms
3
Bureau of Alcohol, Tobacco, Firearms and Explosives. Destructive Device – 26 U.S.C. 5845(f)(2)
4
Office of the Law Revision Counsel. 18 U.S.C. 922 – Unlawful Acts
5
Bureau of Alcohol, Tobacco, Firearms and Explosives. National Firearms Act
6
Federal Register. Changes to National Firearms Act Tax Remittance Provisions
7
Office of the Law Revision Counsel. 26 U.S.C. 5811 – Transfer Tax
8
Office of the Law Revision Counsel. 26 U.S.C. 5812 – Transfers
9
Bureau of Alcohol, Tobacco, Firearms and Explosives. NFA Responsible Person Questionnaire (ATF Form 5320.23)
10
Bureau of Alcohol, Tobacco, Firearms and Explosives. eForms Applications
11
Bureau of Alcohol, Tobacco, Firearms and Explosives. Firearms Forms
12
Federal Register. Removing CLEO Notification Under the National Firearms Act
13
Bureau of Alcohol, Tobacco, Firearms and Explosives. Application to Transport Interstate or to Temporarily Export Certain National Firearms Act (NFA) Firearms
14
GovInfo. 26 U.S.C. 5852 – Transfers to Heirs or Estate Beneficiaries
15
Office of the Law Revision Counsel. 26 U.S.C. 5871 – Penalties
16
Office of the Law Revision Counsel. 18 U.S. Code 3571 – Sentence of Fine