Check Washing: How to Protect the Checks You Mail

You mailed a $150 check to your plumber. Two weeks later, your bank shows it cleared for $4,800, payable to a name you’ve never seen. That’s check washing, and it starts with something as ordinary as raising the flag on your mailbox.

Checks are still everywhere: rent, contractors, insurance premiums, payroll at small businesses, gifts in birthday cards. Each one that travels through the mail carries your name, bank, account number, routing number and signature. Here’s how thieves exploit that, and the practical steps that stop most of it.

What check washing is and why it’s surging

Check washing is when a thief steals a check, uses chemicals such as nail polish remover or other solvents to erase the payee name and amount, then rewrites it to themselves or a fake identity for a larger sum. Your signature stays, so the check looks legitimate.

Stolen checks get used in other ways too. Criminals may deposit them unaltered with a forged endorsement, or copy your account details to print counterfeit checks.

The scale is serious. In a February 2023 alert, the Treasury’s Financial Crimes Enforcement Network (FinCEN) reported a nationwide surge in mail theft-related check fraud. Banks filed more than 680,000 suspicious activity reports about check fraud in 2022, nearly double the roughly 350,000 filed in 2021. FinCEN said criminals target personal, business, tax refund and government benefit checks.

The federal government itself has pulled back from paper. Executive Order 14247, signed in March 2025, directed the Treasury to stop issuing most paper checks for federal payments starting September 30, 2025, partly because Treasury checks are far more likely than electronic transfers to be lost, stolen or altered.

Where checks get stolen

Most washed checks are taken in transit. The common weak points:

• Home mailboxes with the flag up. A raised flag tells anyone driving by that outgoing mail is waiting.
• Blue collection boxes after the last pickup. Mail sitting overnight is an easy target, and thieves sometimes use stolen or copied keys.
• Office mail trays and building lobbies where outgoing mail sits unattended.
• Incoming mail. Refund checks, benefit checks and new checkbooks can be stolen on the way to you.

How to protect checks you mail: 8 steps

These steps come largely from US Postal Inspection Service guidance. None costs much, and together they shut down most opportunities.

1. Drop checks inside the post office. Use the letter slots inside, or hand mail to your carrier. If you must use a blue box, go before the last pickup time posted on it.
2. Never leave outgoing checks in your mailbox overnight or with the flag up.
3. Use permanent ink. Write with a pen that uses indelible black ink or gel ink sold as fraud-resistant. Ballpoint ink is easier to lift with solvents.
4. Fill every line. Write the payee and amount fully, start at the far left, and draw a line through any empty space so nothing can be added.
5. Keep extra data off checks. Don’t write your Social Security number, driver’s license number, card numbers or phone number on them.
6. Use envelopes that hide the contents. Security-tinted envelopes keep a check from being spotted through the paper.
7. Order checks with security features. Many check printers offer features such as chemical-sensitive paper, microprinting and heat-reactive ink that make washing harder or more obvious.
8. Confirm the payment arrived. For larger checks, ask the recipient to confirm receipt, and check that the cleared check’s endorsement matches who you paid.

Key takeaway: The cheapest fix is behavioral: get checks out of your hands and into a locked post office slot or a carrier’s hands, and write them in permanent ink with no blank space.

Catch problems fast with your bank’s tools

Prevention reduces risk, but monitoring is what limits the damage. A washed check usually clears within days, and the sooner you report it, the better your chances.

Turn on alerts. Most banking apps let you get a notification when a check clears or when any withdrawal goes over an amount you set. Our guide to banking app security settings walks through the most useful ones.

Look at check images. Your bank’s app or website usually shows the front and back of every cleared check. Compare the payee, amount and endorsement with what you wrote.

Review statements promptly. Under the Uniform Commercial Code (section 4-406), adopted in some form by every state, customers must review statements with reasonable promptness and report unauthorized signatures or alterations. If you don’t report an altered check within 1 year of the statement being made available, you lose the right to make the bank cover it. Your account agreement may set shorter deadlines. This is not legal advice.

Positive pay for businesses

If your business writes checks, ask your bank about positive pay. You upload a list of each check you issue (number, date, amount and often payee). When a check is presented, the bank compares it to your list and flags any mismatch for you to approve or reject.

Banks usually charge a monthly fee for positive pay, and pricing varies, so ask your bank for its business treasury services menu.

Protect incoming checks and your checkbook

Thieves also target mail coming to you.

• Sign up for USPS Informed Delivery. It’s free and emails you grayscale images of letter mail arriving that day, so you’ll notice if an expected check or checkbook doesn’t show up.
• Collect mail promptly and put a hold on mail when you travel.
• Pick up new checkbooks at your branch instead of having them mailed, if your bank allows it.
• Store blank checks securely and shred old ones you won’t use.
• Choose direct deposit for refunds, paychecks and benefits.

Replace checks with electronic payments

The surest way to avoid check washing is to mail fewer checks. Most regular payments have a safer option.

For checks you receive, mobile deposit keeps them out of the mail entirely. Our guide to how mobile check deposit works explains holds and limits.

What to do if your check was washed

1. Call your bank right away. Report the altered check, ask them to stop payment on any outstanding checks, and ask whether you should close the account and open a new one with a new number.
2. Request copies of the fraudulent check, front and back.
3. File a report with the US Postal Inspection Service at uspis.gov/report or 1-877-876-2455 if the check was stolen from the mail.
4. File a police report. Banks often ask for one.
5. Report identity theft at IdentityTheft.gov if the thief used your personal details beyond the check, and consider the steps in our guide to protecting yourself from identity theft.
6. Tell the person you paid and send payment another way once your account is secure.

For other agencies that take fraud reports, see how to report a scam.

Where to start this week

If you only do 3 things, do these:

1. Stop using your home mailbox for outgoing checks starting today.
2. Turn on check-clearing and large-withdrawal alerts in your banking app.
3. Move your next recurring check payment, such as insurance or rent, to bill pay or direct transfer.

Business owners should add a fourth: call your bank and ask what positive pay costs.

The bottom line

Check washing is low-tech crime that works because checks spend days in unattended mailboxes with everything a thief needs printed on them. You can’t make a paper check theft-proof, but you can make yours a poor target: mail it securely, write it in permanent ink, watch your account closely and replace as many checks as possible with electronic payments.

Sources

• FinCEN: Alert on nationwide surge in mail theft-related check fraud — 2021 and 2022 check fraud SAR volumes, types of checks targeted
• US Postal Inspection Service: Report mail theft — where to report stolen mail and checks
• USPS: Informed Delivery — free daily previews of incoming letter mail
• Executive Order 14247: Modernizing Payments To and From America’s Bank Account — federal paper check phase-out effective September 30, 2025
• Cornell Law School LII: UCC § 4-406 — customer duty to review statements and the 1-year reporting limit