The six NFA categories
The National Firearms Act of 1934 (and amendments in 1968 and 1986) regulates six categories of firearms and accessories. All require a tax-paid transfer and ATF approval before a civilian can possess one.
- Suppressors ("silencers"). Any device that reduces the report of a firearm. By far the most commonly purchased NFA item. $200 tax stamp.
- Short-Barreled Rifles (SBRs). Rifles with barrels under 16" or overall length under 26". $200 tax stamp.
- Short-Barreled Shotguns (SBSs). Shotguns with barrels under 18" or overall length under 26". $200 tax stamp.
- Machine guns. Any firearm that fires more than one round per trigger pull. Civilian ownership of machine guns manufactured AFTER May 19, 1986 is prohibited. Pre-1986 transferable machine guns trade for $20,000+ on the collector market. $200 tax stamp.
- Destructive Devices (DDs). Grenades, large-bore firearms (typically > 0.5" bore), explosive projectiles. $200 tax stamp. Very rare for civilians.
- Any Other Weapons (AOWs). A catch-all category: smoothbore handguns, pen guns, cane guns, certain shotgun configurations. $5 transfer tax (the only NFA category with a reduced tax).
The tax stamp process — buying a suppressor
Concrete walkthrough of the most common NFA purchase:
- Choose a suppressor and a Class 3 dealer. Class 3 / SOT dealers are FFLs who've paid the Special Occupational Tax to deal in NFA items. National retailers (Silencer Shop, Capitol Armory) and many local FFLs are SOTs.
- Pay for the suppressor + the $200 federal tax stamp. The dealer holds the item until ATF approves the transfer to you.
- Fingerprints + passport-style photos. Done in person at the dealer or at any fingerprinting kiosk. Most SOT dealers handle this in-house.
- Submit ATF Form 4 — electronically via the ATF eForm portal in almost all cases now. The dealer initiates and you certify your half.
- CLEO notification. A copy of the Form 4 is sent to your local Chief Law Enforcement Officer (sheriff or police chief). They don't need to approve — they just need to be notified.
- Wait. Currently 7-90 days for e-filed Form 4. Old paper forms ran 6-18 months — that's mostly behind us.
- Pick up. Dealer receives your approved Form 4 with the tax stamp. You go back, sign for the suppressor, and walk out with your new NFA item. Keep a copy of the approved form with the item.
Form 4 vs Form 1 vs Form 5
| Form | Use case | Tax |
|---|---|---|
| Form 4 | Tax-paid transfer from a dealer to a civilian | $200 ($5 for AOW) |
| Form 1 | Make-your-own (build an SBR, make a suppressor from a kit, etc.) | $200 |
| Form 5 | Tax-free transfer (estate inheritance, transfer to law enforcement) | $0 |
| Form 5320.20 | Approval to take SBR / SBS / MG across state lines | $0 |
Form 1 — make your own SBR or suppressor
A Form 1 lets you (rather than a manufacturer) make an NFA item. The common case is taking a pistol-configured AR and SBR-ing it — adding a stock and shortening the barrel under 16".
- File the Form 1 BEFORE you make any modifications. Possession of an unregistered SBR (even briefly) is a federal felony.
- You can't SBR a complete factory rifle and then de-SBR it back — the serialized lower has been registered as an SBR and stays that way until ATF processes a destruction-of-registration.
- E-filed Form 1s currently approve in days to weeks. Paper Form 1s run months.
- The $200 tax applies even though you're making it yourself.
Common NFA mistakes
- Possessing an unregistered NFA item. Federal felony, $250,000 fine, 10 years in prison. Don't. If you inherit a suppressor or SBR from a family member without paperwork, contact a firearms attorney before doing anything else.
- Crossing state lines with an SBR or MG without Form 5320.20 approval. The form is free and fast — but it has to be approved BEFORE you leave.
- Loaning an NFA item to someone outside your trust. Only registered owners (or persons on the trust) can possess. Letting a friend shoot your suppressor at the range is technically a transfer.
- SBR configuration with a 'pistol brace.' The 2023 ATF brace rule is still in legal flux as of 2025-2026. Some configurations are SBRs requiring registration; some are pistols; the regulatory state is unsettled. When in doubt, consult a firearms attorney.
State NFA restrictions
Even if federal law allows an NFA item, some states ban civilian ownership of specific categories:
- Suppressors prohibited (8 states + DC): California, Delaware, Hawaii, Illinois, Massachusetts, New Jersey, New York, Rhode Island.
- SBRs prohibited (varies): California, Hawaii, Illinois, Massachusetts (with caveats), New Jersey, New York (with caveats), Rhode Island.
- Machine guns: Most states allow pre-1986 transferable MGs. California, DC, Hawaii, Illinois, Iowa, Kansas, Minnesota, New Jersey, New York, Rhode Island, and Washington have additional restrictions.
State law changes. Verify before you buy.