Lying in an affidavit is perjury, a federal felony punishable by up to five years in prison and a fine. The criminal charge is only part of it. The judge handling your case can strike the affidavit, order you to pay the other side’s legal costs, dismiss your claims outright, or reopen a judgment years after it became final. A single false statement about your income, your whereabouts, or what you knew and when is enough to trigger any of it.
What Counts as Perjury
Not every error in an affidavit is a crime. Federal law requires three things. You signed the document under oath or under penalty of perjury. The false statement was “material,” meaning it could have influenced the outcome of the proceeding. And you knew it was false when you made it.1Office of the Law Revision Counsel. 18 U.S. Code 1621 – Perjury Generally A faulty memory or an honest mistake doesn’t qualify.
Materiality is broader than people assume. The lie doesn’t have to be about the central issue. If you falsely state in a custody affidavit that you were home on a particular evening, that’s material whenever the court is weighing your fitness as a parent, even if the case ultimately turns on something else. Courts ask whether the statement had the potential to matter, not whether it changed the result.
Intent is where most perjury cases live or die. Prosecutors have to prove you deliberately lied, not that you were careless or confused. That’s why charges almost always arise when the sworn statement contradicts documentary evidence or your own prior sworn testimony, because those contradictions make the “I just forgot” defense collapse.
Criminal Penalties
Federal perjury is a felony punishable by up to five years in prison, a fine, or both.1Office of the Law Revision Counsel. 18 U.S. Code 1621 – Perjury Generally It applies whether the false affidavit was filed in federal court, submitted to a federal agency, or otherwise covered by a federally authorized oath. Federal charges must be brought within five years of the date you submitted the false affidavit, not when it was discovered.2Office of the Law Revision Counsel. 18 U.S. Code 3282 – Offenses Not Capital
State penalties vary but track the same shape. Most states classify perjury as a felony, with prison sentences typically running from two to seven years depending on the jurisdiction and the seriousness of the underlying case. A few states treat perjury in minor civil matters as a lesser offense; others impose harsher penalties when the false statement affects a criminal prosecution. Wherever you live, a conviction leaves you with a permanent felony record and the long-term fallout that comes with it for employment, professional licensing, and civil rights.
You don’t need to be the one who signed the affidavit. Federal law treats “subornation of perjury,” meaning persuading or pressuring someone else to lie under oath, as its own crime with the same maximum penalty of five years and a fine.3Office of the Law Revision Counsel. 18 U.S. Code 1622 – Subornation of Perjury Drafting a false affidavit for someone else to sign, coaching a witness on what to swear to, or paying for a fabricated statement all put you in reach of prosecution even though your name never appears on the document.
One narrow area where penalties climb much higher: false statements in immigration documents, including visa applications, asylum claims, and naturalization petitions. Federal law reaches 10 to 25 years of prison exposure in that context, along with denial of the application, deportation, and permanent bars on future immigration benefits.
What the Judge in Your Case Can Do
The criminal case is the headline, but the more likely consequence is what happens inside the proceeding where you filed the affidavit. A judge who sees a false sworn statement doesn’t need a prosecutor to act. Courts have broad inherent authority to sanction parties who abuse the legal process, and a false affidavit is one of the clearest abuses there is.
What the court can do:
- Strike the affidavit from the record, so any motion or argument that depended on it collapses.
- Order you to pay the other side’s attorney’s fees and costs, including what it took to uncover the lie.4Legal Information Institute. Federal Rules of Civil Procedure Rule 11
- Dismiss your claims or enter default judgment against you. Judges reserve this for egregious misconduct, and a deliberately fabricated affidavit is exactly the kind of conduct that fits.
- Hold you in contempt of court, which carries its own fines or jail time independent of any perjury prosecution.
These sanctions apply whether or not criminal charges follow. A prosecutor might pass on the case for reasons that have nothing to do with the strength of the evidence, and the civil judge still has every tool needed to punish the lie inside the case itself.
A Case You Won Can Be Reopened
Here is the consequence that catches people off guard. A case you already won can be undone if the other side later finds out your affidavit was false. Federal rules let a court grant relief from a final judgment based on “fraud, misrepresentation, or misconduct by an opposing party.” The ordinary motion has to be filed within a year, but for fraud on the court, there is no time limit at all. The court keeps the power to set aside a judgment obtained through fraud indefinitely.5Legal Information Institute. Federal Rules of Civil Procedure Rule 60 – Relief from a Judgment or Order
So the lie doesn’t just risk consequences while the case is live. It creates a vulnerability that follows the judgment forever. If an ex-spouse later discovers you concealed assets in a divorce affidavit, or a business opponent uncovers fabricated evidence after settling, the door to reopening the matter never fully closes. The five-year criminal clock may run out. The civil door doesn’t.
Unsworn Declarations Count Too
A common misconception: because a document wasn’t notarized, it isn’t really an affidavit and perjury doesn’t apply. That’s wrong. Federal law gives an unsworn written declaration the same legal weight as a sworn affidavit, provided it includes specific language stating it is made “under penalty of perjury” and is signed and dated.6Office of the Law Revision Counsel. 28 U.S. Code 1746 – Unsworn Declarations Under Penalty of Perjury
For a declaration signed inside the United States, the required language is: “I declare under penalty of perjury that the foregoing is true and correct,” followed by the date and your signature.6Office of the Law Revision Counsel. 28 U.S. Code 1746 – Unsworn Declarations Under Penalty of Perjury Most federal and state courts accept these interchangeably with notarized affidavits, and signing one with a false statement carries the same perjury exposure as raising your right hand in front of a notary.
How False Affidavits Get Caught
People who lie in affidavits tend to overestimate how hard the lie will be to detect. Discovery is built to test factual claims, and affidavits are easy targets because they pin you to specific statements that can be checked against other evidence.
Depositions
The most common way a false affidavit unravels is in a deposition. The opposing attorney walks through the affidavit line by line, asking for the kind of surrounding detail a truthful person remembers easily and a liar has to invent on the spot. Inconsistencies between the deposition and the written affidavit are powerful evidence of perjury, because now there are two different sworn stories.
Contradictory Documents
Emails, financial records, text messages, GPS data, security footage, and social media posts all create independent records of what actually happened. Swear you were home on a particular date, and a credit card charge from another city or a geotagged photo tells a different story. Financial affidavits in divorce cases are especially exposed, because bank statements, tax returns, and employment records leave a trail that is almost impossible to falsify all the way through.
Digital Forensics
When the document itself is suspect, forensic analysis can show whether it was altered or backdated. Every digital file carries metadata recording when it was created, modified, and by whom. An affidavit claiming a contract was signed on a particular date can collapse when metadata shows the file was actually created weeks later. Courts increasingly accept this kind of evidence, and the tools are sophisticated enough to catch subtle manipulations.
Prosecutions Are Rare. Consequences Aren’t.
Perjury prosecutions are uncommon despite the serious penalties on the books. Prosecutors work with limited resources and tend to prioritize cases where the false statement caused real harm or obstructed a significant proceeding. A false affidavit in a routine civil dispute rarely draws a district attorney’s attention, no matter how blatant it is.
The evidentiary burden is also genuinely hard. Showing someone knowingly lied, rather than remembered events differently, takes proof of intent that goes beyond showing the statement was wrong. Prosecutors usually want documentary evidence that the person knew the truth and chose to state the opposite, which is why perjury charges most often arise when a sworn statement directly contradicts the signer’s own prior writings or recorded statements.
Rare prosecution is not the same as safe behavior. The civil consequences get imposed by judges who see the false statement firsthand and don’t need a prosecutor’s involvement. Most people who lie in affidavits don’t go to prison. They do lose credibility with the court, absorb sanctions that damage their case, and create a record that can resurface whenever someone looks hard enough.