Keeping extra change you know you weren’t owed is illegal in most states. Simply walking out of a store with a few extra dollars because the cashier miscounted may feel like a windfall, but under the law it can be theft. Whether you’re actually at risk of charges depends on one thing above all: what you knew, and when you knew it.
When Keeping Extra Change Crosses Into Theft
Most states follow a principle rooted in the Model Penal Code: if you receive property by mistake and you know it was a mistake, keeping it without making a reasonable effort to return it is theft. The textbook example is a cashier handing you change for a $50 when you paid with a $20. If you notice at the counter and say nothing, you’ve moved from lucky break to criminal conduct in most jurisdictions.
There is no minimum dollar amount built into the legal principle. Prosecutors generally don’t pursue a case over a dollar or two, but the rule itself doesn’t excuse small sums. A store that reviews security footage and spots a customer repeatedly pocketing cashier errors has grounds to press charges even when each incident is minor.
What “Honest Mistake” Actually Means
The knowledge element is what separates a crime from an accident. If you shove your change in your pocket without counting it and only notice the extra bill at home, you haven’t committed theft at the register. You weren’t aware of the error when it happened, so there was no intent to take what wasn’t yours.
The obligation kicks in the moment you become aware. Once you know the money isn’t yours, continuing to keep it, spend it, or hide it creates legal exposure. The reasonable response is to go back, call the store, or otherwise make an effort to return the overpayment. What counts as “reasonable” varies with the amount and the circumstances. Driving an hour back for an extra quarter is not required. Keeping an extra $40 because you didn’t feel like turning the car around is a different story.
The practical risk of prosecution usually scales with the amount and with any evidence of intent. A one-time slip is rarely charged. A pattern, a large sum, or video showing you counting the money and smiling before leaving changes the picture.
The Same Rule Applies to Other Overpayments
The legal principle isn’t specific to cash registers. If a bank accidentally credits extra funds to your account, or if someone sends you money by mistake through a payment app, spending those funds instead of reporting the error can lead to theft or fraud charges. Courts treat all of these situations the same way: money you know isn’t yours that you intentionally keep.
This matters because people often think a bank’s or an app’s mistake somehow becomes their good fortune once the money lands in their account. It doesn’t. The institution can reverse the transfer, demand repayment, and in cases involving larger sums or clear evidence of intent, refer the matter for prosecution.
Counterfeit Bills in Your Change
A related worry when you receive change: what if one of the bills is fake? Receiving counterfeit currency unknowingly is not a crime. The statutes that criminalize passing or possessing counterfeit money all turn on the word “knowingly.” If a cashier hands you a bogus $20 and you spend it later without ever suspecting it was fake, you haven’t broken the law.1GovInfo. 18 USC 472 – Uttering Counterfeit Obligations or Securities
Once you suspect a bill is counterfeit, the calculus changes. Trying to pass it along after that point is a federal offense carrying up to 20 years in prison. Manufacturing counterfeit currency carries the same maximum under a separate statute.2Office of the Law Revision Counsel. 18 USC 471 – Obligations or Securities of United States If you believe a bill you received is fake, the Secret Service advises turning it over to law enforcement or your bank rather than trying to spend it.
Having a Lot of Change at Home Isn’t the Problem
One thing worth separating from the overpayment question: there is no federal law that limits how much U.S. currency a person can keep. Coins and bills are legal tender, and the government places no cap on how much any individual can hold.3Office of the Law Revision Counsel. 31 U.S. Code 5103 – Legal Tender A jar of quarters on the counter, a shoebox of bills in the closet, a bucket of rolled pennies in the garage — all legal to possess.
What draws legal attention is never the raw amount. It’s where the money came from, how you use it, and whether you report it when the law requires reporting. Keeping change is fine. Keeping change you knew was handed to you by mistake is not.
If You Realize Later That You Were Overpaid
People often don’t notice an overpayment until they’re already home. At that point, the honest step is also the legally safest one: contact the business, explain what happened, and return the difference. Most stores will note the correction and move on. The documentation of your effort to return the money is itself protection if the store later reviews its tills and identifies the shortage.
Doing nothing after you realize is where real risk begins. The longer you hold money you know isn’t yours, the harder it becomes to argue the keeping was anything other than deliberate.