To make an AR-15 lower into an SBR legally, file ATF Form 1 (Form 5320.1) through the eForms system, wait for your approved tax stamp to come back, then engrave the required maker’s markings and assemble the rifle. As of January 1, 2026, the NFA making tax for short-barreled rifles is $0, down from $200, and eForm 1 approvals are averaging about 14 days.1Bureau of Alcohol, Tobacco, Firearms and Explosives. Current Processing Times Assembling the short configuration before that approval arrives is a federal felony, so the order of operations matters.
What Counts as an SBR
Federal law defines a short-barreled rifle as a rifle with a barrel shorter than 16 inches, or any weapon made from a rifle with an overall length under 26 inches.2LII / Legal Information Institute. 18 USC 921(a)(8) – Definition: Short-Barreled Rifle Your lower receiver is the legally regulated firearm. The moment you attach a stock and a barrel shorter than 16 inches to that lower without an approved Form 1, you have committed an offense that carries up to 10 years in prison and a $10,000 fine.3Office of the Law Revision Counsel. 26 USC 5871 – Penalties
How your lower was originally transferred on the Form 4473 also affects what you can do with it while you wait. A stripped lower transferred as “other/firearm” can be built as a pistol (short barrel, no stock) in the meantime. A lower that was first transferred or assembled as a rifle must stay in rifle-legal configuration until the stamp arrives. Swapping a rifle lower to a short barrel before approval is illegal whether or not a stock is attached.
Don’t Buy the Short Upper Yet
Federal prosecutors use a doctrine called constructive possession. If you own all the parts needed to build an unregistered SBR and no lawful use for them in that combination, you can be charged as if you had already built it. Owning a rifle-stocked lower and a 10.5-inch upper in the same house, without a tax stamp, gives the ATF grounds to argue you possess an illegal SBR even with the parts in separate rooms. Wait to buy the short upper until your Form 1 comes back, or keep the upper somewhere separate from any stocked lower you own.
Check Your State Law First
Federal approval does not override state law. As of 2026, California, Hawaii, New Jersey, New York, Rhode Island, and the District of Columbia prohibit short-barreled rifles entirely, even with a valid federal tax stamp. Other states allow SBRs but impose their own registration or restrictions. Confirm your state and local rules before you file anything, because an approved federal stamp will not protect you from a state felony.
Are You Eligible to File
You must be at least 21 to file a Form 1. Federal law also bars several categories of people from possessing any firearm, including NFA items.4Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts You cannot lawfully make an SBR if any of the following apply:
- A felony conviction, meaning any crime punishable by more than one year in prison, regardless of sentence served
- Fugitive from justice status
- Unlawful drug use or addiction, including marijuana even in states where it is legal (the ATF revised its approach in early 2026 to focus on patterns of use rather than a single instance within the past year)
- Having been adjudicated a mental defective or committed to a mental institution
- Certain non-citizen status, including unlawful presence and most nonimmigrant visas
- Dishonorable discharge from the military
- Renunciation of U.S. citizenship
- A qualifying domestic violence restraining order
- A misdemeanor domestic violence conviction
Filing anyway leads to denial, and building the SBR after denial carries the same 10-year federal penalty as building without ever filing.
File as an Individual or Through a Trust
You can file Form 1 as an individual or through a legal entity, most commonly a gun trust. The choice controls who can lawfully possess the finished SBR.
Register as an individual and you are the only person who may possess the firearm. If your spouse picks it up at the range while you walk to the car, that is technically an unauthorized transfer. A gun trust lists co-trustees who can all lawfully possess and use the SBR without the registered owner present. Trusts also simplify inheritance, since the trust survives the original owner.
The tradeoff is cost and paperwork. An attorney-drafted NFA trust typically runs $60 to $250. Every “responsible person” on the trust must individually submit fingerprint cards, a passport-style photo, and ATF Form 5320.23, the Responsible Person Questionnaire.5Bureau of Alcohol, Tobacco, Firearms and Explosives. Application to Make and Register NFA Firearm – ATF Form 5320.1 Four trustees means four sets of fingerprints and photos. A single person with no co-possession needs is usually better off filing individually.
Filing ATF Form 1
The application to make and register your SBR is ATF Form 5320.1.6Bureau of Alcohol, Tobacco, Firearms and Explosives. Application to Make and Register a Firearm – ATF Form 1 (5320.1) You will need:
- Firearm details: the lower receiver’s manufacturer, model, serial number, caliber, and the barrel length and overall length you plan to build
- Two completed FBI Form FD-258 fingerprint cards (blue-line version) per applicant or per responsible person on a trust
- One 2×2-inch passport-style photograph taken within the last six months
- ATF Form 5320.23 for each responsible person, if filing through a trust or entity
The statute requires that you file the application, pay any applicable tax, submit identification including fingerprints and a photograph, and receive ATF approval before making the firearm.7GovInfo. 26 USC 5822 – Making As of January 1, 2026, the SBR making tax is $0. You still complete the full NFA process; there is simply no tax payment to submit.
CLEO Notification
Send a copy of your completed Form 1 to the Chief Law Enforcement Officer with jurisdiction over your address. If you file through a trust, a copy of each responsible person’s Form 5320.23 goes to that person’s respective CLEO.5Bureau of Alcohol, Tobacco, Firearms and Explosives. Application to Make and Register NFA Firearm – ATF Form 5320.1 This is a notification only. The CLEO does not sign, approve, or need to respond. Your local sheriff, chief of police, or equivalent usually fills the role.
Use eForms
The ATF’s eForms system is the standard filing path, and Form 1 is available electronically.8Bureau of Alcohol, Tobacco, Firearms and Explosives. eForms Applications As of January 2026, the ATF reports an average eForm 1 processing time of 14 days, compared to 38 days for paper.1Bureau of Alcohol, Tobacco, Firearms and Explosives. Current Processing Times Those averages move with application volume, but eForms is consistently faster. Paper submissions in duplicate are still accepted by mail to the NFA Division, though there is little reason to choose paper unless you cannot create a digital account.
After Approval: Engrave, Then Assemble
When the approved Form 1 comes back, you have permission to build. Do not assemble the short configuration before that approval arrives, even if the wait runs longer than the posted average.
Before or after assembly, engrave the firearm with the maker’s identification. The required markings are your name (or the trust name) and the city and state where you manufacture the SBR. They must be placed on the frame, receiver, or barrel, cut at least 0.003 inches deep, and printed no smaller than 1/16 inch.9Bureau of Alcohol, Tobacco, Firearms and Explosives. NFA Handbook – Chapter 7 – Manufacturing NFA Firearms The serial number specifically must appear on the receiver.10Bureau of Alcohol, Tobacco, Firearms and Explosives. NFA Handbook – Chapter 6 – Making NFA Firearms by Nonlicensee
Most people use a local shop that handles NFA engraving. Professional work typically runs $50 to $125. Laser engraving is common, but confirm the shop can hit the 0.003-inch depth minimum, because some laser methods leave marks that are too shallow to comply. Keep a copy of your approved Form 1 with the firearm or on your phone. There is no legal duty to carry the stamp, but producing it quickly prevents complications if you encounter law enforcement.
Staying Legal After the Build
Only you (or your co-trustees) may possess the finished SBR. Storing it where another person can access it without authorization looks like an unregistered transfer. In a shared household, keep it locked in a container that only you can open. The same rule applies at a friend’s house or in a safe-deposit box: you must maintain exclusive access. A roommate who knows the safe code, a spouse who isn’t on the trust, or a range buddy who borrows the rifle while you step away can each create an unauthorized possession problem. If anyone in your household will need access, register through a trust and name them as a co-trustee.
Taking the SBR across a state line requires advance ATF approval. Submit ATF Form 5320.20 to the NFA Division and wait for written approval before you leave.11Bureau of Alcohol, Tobacco, Firearms and Explosives. ATF Form 5320.20 – Application to Transport Interstate or to Temporarily Export Certain NFA Firearms The form covers both temporary trips and permanent moves and can be filed through eForms.12Bureau of Alcohol, Tobacco, Firearms and Explosives. Application to Transport Interstate or Temporarily Export Certain NFA Firearms – ATF Form 5320.20 Also confirm the destination state allows SBRs. Driving a registered SBR into a state that bans them is a state-level crime regardless of your federal paperwork.