Overpayment Scams: Why a "Too Good to Be True" Refund or Payment Is a Red Flag

Picture this: you listed a sofa on Craigslist for $300. A buyer contacts you quickly, seems friendly, and mails you a check for $800. They apologize for the mix-up and ask you to deposit the check and wire back the $500 difference. You can see the money sitting in your account. It feels real. You trust it.

That check is fake. The money you see isn't yours yet. And if you wire that $500, it's gone.

This is an overpayment scam, and it's one of the most reliably effective frauds out there. Not because people are gullible, but because it weaponizes the banking system against you in a way most people don't know is possible. Once you understand the mechanic, every version of this scam becomes easy to recognize.

What is an overpayment scam?

An overpayment scam works like this: a scammer sends you a fraudulent payment for more than an agreed amount, then asks you to return the difference using your own real money. You send it. Then the original payment bounces. You've lost what you sent, and your bank may recover the deposited amount from your account balance too.

Every variant of this scam follows that same structure: fake payment in, real money out.

The reason it works comes down to a gap in how banking operates. Federal law requires banks to make deposited funds available within one to two business days. But actually verifying that a check is genuine can take weeks, sometimes longer for checks drawn on foreign banks. Scammers exploit that window. By the time your bank figures out the check is fraudulent, you've already sent the "difference" from your own funds. According to the FTC, fake checks can take weeks to be discovered and untangled, and by then, you're on the hook. For a deep look at how this plays out specifically on Facebook Marketplace, see our guide on the payment scam targeting marketplace sellers.

The five most common setups

Overpayment scams show up in a lot of different contexts. The packaging changes. The core mechanic never does.

Online selling is where this scam started. A buyer responds to your Craigslist, OfferUp, or Facebook Marketplace listing, sends a check for far more than your asking price, and asks you to wire back the difference. They may claim the overpayment was a mistake, or that extra funds need to cover shipping costs.

Job offer scams have grown dramatically. Reports to the FTC about job scams tripled from 2020 to 2024, with reported losses jumping from $90 million to $501 million in that same period, according to FTC data. In a typical version, a scammer posing as an employer sends you a "starter check" and asks you to wire part of it for equipment or supplies.

Rental scams follow the same playbook. A fake landlord or subtenant sends a check that exceeds what's owed and asks you to forward the rest to a third party, often a "moving company" that doesn't exist.

Tech support and refund scams skip the check entirely. A scammer calls pretending to be Amazon, Microsoft, or a bank, claims they accidentally sent you too much of a refund, and asks you to send the excess back via gift card or wire transfer. In some versions, they use remote access software to display a fake bank balance on your screen that makes the transfer look real.

Romance scams often build trust over weeks or months before a check arrives. The scammer frames it as a gift or business arrangement, then creates urgency around sending money back.

Why fake checks temporarily clear (the banking loophole)

This is the part most people find hard to believe, and it's the reason the scam works so well.

When you deposit a check, your bank makes funds available within one to two business days as required by federal law. That's not the same as the check being verified. Verification can take weeks, and often longer for checks drawn on foreign banks. Some foreign institutions take more than 20 business days to pass credit, according to the Federal Reserve's Foreign Check User Guide.

Scammers know this better than most bank customers do. They time the request to return money for the window right after your funds appear available, before the fraud is detected.

When the check eventually bounces, your bank reverses the deposit. That means the money you saw in your account disappears, and anything you wired out of pocket is gone permanently. You end up short twice.

A cashier's check doesn't make this safer. Fake cashier's checks are common and equally worthless. Seeing "cashier's check" on the payment doesn't mean it's been verified.

Red flags to spot an overpayment scam

Once you know what to look for, these situations become obvious quickly.

• The payment is more than the agreed amount. Any buyer, employer, or renter who sends you more than you're owed and asks for the difference back is running this scam.
• They have a detailed story for the mistake. The explanations are always plausible. Customs fees, assistant error, international accounts. Don't let the story distract from the pattern.
• They want money back via wire transfer, gift card, Zelle, or Venmo. These methods are irreversible. Scammers insist on them for exactly that reason.
• There's urgency. "Please do this today" or "I need this before tomorrow" is pressure built to stop you from thinking it through.
• Contact moved off-platform fast. If a buyer on a marketplace immediately asked you to text or email instead of messaging through the app, they're avoiding the platform's fraud detection.
• The check arrived before you agreed to anything. Legitimate buyers don't send payment before a deal is confirmed.
• They say they're overseas or can't meet in person. This explains why everything happens remotely, and why you'd never spot the fraud in real time.

What to do if it's already happened

If you've already sent money, don't panic. And don't send more.

Contact your bank immediately. Tell them the check you deposited may be fraudulent and that you've already sent funds. Acting quickly gives you the best chance of stopping or reversing an outgoing wire before it settles.

Report it to the FTC at ReportFraud.ftc.gov. The FTC uses these reports to track fraud patterns and support enforcement. Consumers reported losing more than $12.5 billion to fraud in 2024, a 25% jump over the prior year, according to the FTC. Your report adds to that picture.

File a complaint with the Internet Crime Complaint Center (IC3) at ic3.gov if any part of the contact happened online.

Contact the U.S. Postal Inspection Service at USPIS.gov if a physical check arrived by mail.

Save everything. Keep all text messages, emails, screenshots, and the check itself if you have it. These records help investigators and could support any recovery effort.

Recovery is difficult, but not always impossible. Quick action matters more than anything else.

Conclusion

The pattern is always the same: someone sends you money first, then needs some back. That's the scam. It doesn't matter if it comes dressed as a job offer, an apartment deposit, a customer overpaying for something you listed, or an unexpected refund call. The mechanic is identical.

You don't need to be a security expert to spot it. You just need to know the rule: money that shows in your account isn't yours until the check has fully cleared, which takes weeks, not days. Any request to send money back before that point is a scam.

Guardio helps flag suspicious links, phishing messages, and scam-related communications before you engage with them. If something arrives in your inbox or browser that doesn't feel right, we'll help you check it before it costs you anything.

Get a free security scan with Guardio today and stay protected from overpayment scams.