Federal law requires a licensed firearms dealer to run your information through the FBI’s National Instant Criminal Background Check System before handing over any firearm, and understanding how gun background checks work starts with what happens in those few minutes at the counter. You fill out a form, the dealer submits your identifying details to NICS, and the system searches federal and state records for anything that would legally bar you from buying. Most checks come back within minutes with one of three answers: proceed, delayed, or denied.
What Happens at the Counter
Every sale by a Federal Firearms Licensee to an unlicensed buyer follows the same sequence. The dealer completes Section A of ATF Form 4473, and you complete Section B, certifying your personal information and answering a series of eligibility questions about criminal history, drug use, mental health, and domestic violence.1Bureau of Alcohol, Tobacco, Firearms and Explosives. ATF Form 4473 – Firearms Transaction Record Revisions Your answers plus your identifying information give the dealer what is needed to initiate the check.2eCFR. 28 CFR 25.6 – Accessing Records in the System
The dealer contacts NICS, which was created by the Brady Handgun Violence Prevention Act signed on November 30, 1993, and has been run by the FBI ever since.3Bureau of Alcohol, Tobacco, Firearms and Explosives. Brady Law The system searches three databases in the background: the National Crime Information Center, the Interstate Identification Index, and the NICS Indices. Between them, they hold criminal history records, outstanding warrants, active protective orders, and records of disqualifying mental health adjudications.
The check produces one of three responses:
- Proceed clears the sale.
- Denied means the sale cannot go forward.
- Delayed means NICS found a potential match with a disqualifying record and the FBI needs more time to sort it out.
Who Is Legally Barred From Buying
Federal law lists nine categories of people prohibited from shipping, receiving, or possessing any firearm or ammunition:4Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts – Section: 922(g)
- Anyone convicted of a crime punishable by more than one year in prison, regardless of the actual sentence served.
- Fugitives from justice, meaning anyone with an outstanding warrant or fleeing prosecution.
- Current users of, or people addicted to, controlled substances under federal drug schedules.
- Anyone a court or other authority has formally found to be a danger to themselves or others, or who has been involuntarily committed to a mental institution.
- Noncitizens unlawfully present in the United States, and most people admitted on a nonimmigrant visa (with limited exceptions such as valid hunting license holders).
- Anyone discharged from the military under dishonorable conditions.
- Former U.S. citizens who have formally renounced their citizenship.
- Anyone subject to a qualifying domestic violence restraining order issued after a hearing that either found a credible threat or explicitly prohibited the use of force against an intimate partner or child.
- Anyone convicted of a misdemeanor crime of domestic violence in any court.
Being under indictment for a felony does not bar you from possessing firearms you already own, but it does bar you from shipping, transporting, or receiving new ones. It is also a separate federal crime to sell or give a firearm to someone you know or have reason to believe falls into any of these categories.5Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts – Section: 922(d)
Delays and the Three-Day Default Proceed Rule
Most NICS checks come back within minutes. When they do not, the Brady Act gives the FBI three business days to reach a final decision. If that window closes without a determination, the dealer may legally complete the sale at their discretion.6Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts – Section: 922(t)(1)(B)(ii) This is often called the default proceed provision.
The FBI does not stop working the case when three days pass. If a later review determines the buyer was in fact prohibited, the ATF is notified and works to retrieve the firearm. Some states have gone further and refused to allow default proceeds under their own laws, meaning no transfer can happen in those states until the check is actually completed.
Extra Steps for Buyers Between 18 and 20
The Bipartisan Safer Communities Act of 2022 created a more thorough process for buyers under 21. When a dealer runs a check on a buyer in that age group, NICS also contacts three sources in the buyer’s state of residence: local law enforcement, the state criminal history or juvenile justice repository, and the state custodian of mental health adjudication records.7Congress.gov. Text – 117th Congress – Bipartisan Safer Communities Act Those agencies search for juvenile records, delinquent acts, and mental health commitments that might disqualify the buyer.8Federal Bureau of Investigation. Crime Data – Bipartisan Safer Communities Act
If no agency flags anything within three business days, the sale can proceed. If any of them reports potentially disqualifying information within that window, NICS gets up to 10 business days from the dealer’s initial contact to investigate and decide.9Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts – Section: 922(t)(1)(C) If you are in this age range, plan for a wait that may run longer than the standard three days.
When a Background Check Is Not Required
Federal law does not require a NICS check when a private individual sells a firearm to another resident of the same state. An ATF guide acknowledges that unlicensed sellers “may not have the ability to conduct complete background checks on potential buyers” and that using a dealer as a middleman “is purely voluntary under federal law.”10GovInfo. Facilitating Private Sales – A Federal Firearms Licensee Guide This exemption applies at gun shows, through classified ads, and in face-to-face sales.
Close to 20 states and the District of Columbia have closed this gap with Universal Background Check laws that require all firearm transfers, including private ones, to run through a licensed dealer. In those states, the private seller brings the buyer to an FFL, the dealer runs NICS, and the transaction proceeds only if the buyer passes. Fees for that service vary by location.
Federal law does still require anyone who is “engaged in the business” of dealing in firearms to hold an FFL and run background checks on every sale, and the Bipartisan Safer Communities Act expanded that definition to reach people who repeatedly buy and resell firearms with intent to predominantly earn a profit. Occasional sales from a personal collection, sales of inherited firearms, and estate auction services are excluded.
How to Appeal a Denial
If NICS denies your purchase, you can challenge the decision. Appeals go to the FBI by mail, fax, or through the online NICS appeals portal, and they must include your full name, mailing address, and the NICS Transaction Number or State Transaction Number from the denied transaction.11Federal Bureau of Investigation. NICS Guide for Appealing Missing information gets the appeal rejected outright, so confirm you have the transaction number before submitting.
The FBI’s Appeal Services Team will send you the general reason for the denial within five business days. If the denial rests on an inaccurate record, you can submit court documentation or other evidence to correct it. If the problem is mistaken identity, you can submit a set of fingerprints so the FBI can distinguish you from the person actually in the flagged record. The agency taking your prints must include its name, address, phone number, and FBI identifier. Cases are worked in the order they arrive, and the FBI responds by mail.
Penalties for Lying or Buying for Someone Else
The eligibility questions on Form 4473 are not casual. Anyone who knowingly makes a false statement on the form faces up to five years in prison, a fine, or both.12Office of the Law Revision Counsel. 18 USC 924 – Penalties – Section: 924(a)(1)(A) A prohibited person who checks “no” to a disqualifying question has committed a federal offense on top of any other charges.
Buying a firearm for someone who cannot pass a check, or who wants to avoid one, is a straw purchase. Under 18 U.S.C. 932, straw purchasing carries a maximum sentence of 15 years in federal prison and a fine of up to $250,000.13Office of the Law Revision Counsel. 18 USC 932 – Straw Purchasing of Firearms If the firearm is meant for use in a felony, an act of terrorism, or a drug trafficking crime, the maximum jumps to 25 years. Before 2022, straw purchases were prosecuted under the general false-statement provision with a five-year cap, so Congress plainly intended a much sharper deterrent.
A related trafficking statute, 18 U.S.C. 933, makes it a crime to ship, transport, or transfer a firearm to someone knowing their possession would be a felony, with a maximum sentence of 15 years.14Office of the Law Revision Counsel. 18 USC 933 – Trafficking in Firearms That provision reaches anyone in the chain of transfer, not just the final seller.