The short answer
Fill in the check completely in indelible black ink with no blank space on the payee or amount lines, seal it in a security envelope, and hand it over inside a Post Office or drop it in a blue collection box before the last pickup rather than leaving it in your home mailbox. For a tracking number and delivery record, add Certified Mail ($5.55 plus postage); for a high-value check, Registered Mail (from $20.90 plus postage, current USPS prices, October 2026) is USPS’s most secure service. Then watch your account until the check clears, and if it goes missing, ask your bank to stop payment and report it to the Postal Inspection Service.
Is it safe to mail a check?
Most mail arrives safely; the Postal Inspection Service says the vast majority of letters and packages reach their destinations. But checks are a favorite target. In a February 27, 2023 alert, FinCEN described a nationwide surge in check fraud tied to mail theft and reported that banks filed more than 680,000 suspicious activity reports for check fraud in 2022, nearly double the 2021 total.
According to that alert, thieves target blue collection boxes, unsecured residential mailboxes, and cluster mailboxes, increasingly with authentic or counterfeit USPS Arrow Keys. They then “wash” stolen checks with chemicals, write in a new payee, and often raise the amount. USPS reported 38,500 high-volume mail theft incidents from mail receptacles, including blue collection boxes, in fiscal year 2022, and in 2023 announced high-security collection boxes and electronic locks in response.
FinCEN says thieves steal every kind of check, from personal and business checks to tax refunds and benefit payments, and that business checks can be especially valuable because the accounts are often well funded and fraud may take longer to notice. Some scammers skip the washing and use copiers or scanners to print fake copies; the Postal Inspection Service says inspectors recover more than $1 billion in counterfeit checks and money orders every year. Mailing a check is still workable if you close the gaps thieves use: an alterable check, mail left sitting in a box, and no one watching the account afterward.
How to fill out a check so it’s hard to alter
Washing works on ink that lifts and on space that can be filled in. The OCC, the national bank regulator, says black gel ink is highly resistant to check washing, and the Postal Inspection Service and American Bankers Association recommend pens with indelible black ink.
- Write in indelible black ink, such as a black gel pen.
- Write the payee’s full name exactly as they asked, and don’t leave blank space on the payee or amount lines.
- Use the memo line for the account or invoice number the payee needs, not for personal details.
- Don’t write your Social Security number, card numbers, driver’s license number, or phone number on the check unless the payee requires it.
- Sign the check last, once everything else is filled in.
Where to drop off a check
Don’t leave an outgoing check in your mailbox with the flag up. USPS’s own advice is not to let incoming or outgoing mail sit in your mailbox, and to deposit outgoing mail inside your local Post Office, at your place of business, or by handing it to a letter carrier. The OCC suggests the letter slots inside the Post Office when you send checks.
If you use a blue collection box, the Postal Inspection Service says to deposit your mail before the last pickup of the day rather than leaving it to wait for the next collection.
Choose an envelope that hides the check
The Postal Inspection Service and American Bankers Association suggest security envelopes to conceal the contents of your mail. Fold the check inside a sheet of paper or the payment stub as well. If the payee sent a window envelope, make sure only the address shows in the window, not the check.
Never put cash in with the check. The Postal Inspection Service’s first rule for valuable mail is not to risk sending cash at all.
What is the safest way to mail a check using USPS?
A First-Class stamp gets a check there, but it gives you no record. Certified Mail adds a mailing receipt and tracking, and USPS keeps a delivery record that includes the recipient’s signature. It travels as ordinary mail and includes no insurance.
Registered Mail is the most secure service USPS offers. It is tracked through a system of receipts from acceptance to delivery, and you must hand it to a retail employee at a Post Office or to a rural carrier. USPS treats a check as a nonnegotiable instrument: you declare no value, or its replacement cost if you want postal insurance. Insurance therefore covers the cost of replacing the check, not its face amount.
| Option | Fee | What you get |
|---|---|---|
| First-Class Mail, 1-ounce letter | $0.82 | Delivery only; no receipt or tracking |
| Certificate of Mailing | $2.45 plus postage | A postmarked record of the date you mailed it |
| Certified Mail | $5.55 plus postage | Mailing receipt, tracking, and a USPS delivery record; no insurance |
| Return Receipt (with Certified Mail) | $2.91 electronic, $4.65 hardcopy | A delivery record with the recipient’s signature sent to you |
| Registered Mail | From $20.90 plus postage | USPS’s most secure service, with receipts from acceptance to delivery; counter or rural carrier only |
Is it safe to send a $10,000 check in the mail?
A large check faces the same risks as a small one, with more at stake, and FinCEN notes that fraudsters often raise the amount on washed checks. If you mail it, Registered Mail is the strongest USPS option, but remember that its insurance covers replacement cost, not the $10,000.
For large sums, ask the payee whether they accept an electronic payment. The Postal Inspection Service and American Bankers Association suggest considering e-checks, ACH payments, and other electronic payments instead of paper checks. Whatever you choose, call the payee to confirm the check arrived.
Track the check until it clears
Watch your account until the check is paid. The OCC recommends account alerts for all transactions and frequent statement reviews. If your bank shows images of paid checks, the Postal Inspection Service and American Bankers Association say to check the back as well: the endorsement should match the payee, because criminals sometimes deposit a stolen check unaltered.
Then confirm with the payee that the check arrived, as USPIS and the ABA recommend. If you’re the one waiting for a check, collect your mail promptly, and if it doesn’t arrive when expected, contact the sender right away; USPS’s Informed Delivery service emails a daily preview of the letters scheduled to reach you.
What to do if a mailed check is lost or stolen
If the payee says the check never arrived and it hasn’t cleared, contact your bank right away to stop payment. The CFPB says banks may charge a fee and that procedures vary; under most states’ laws, a written stop-payment request made before the check is processed keeps it from being cashed for six months, and in some cases the stop lasts a year. To stop it for good, you can close the account and open a new one.
If the check was cashed by someone else, tell your bank as quickly as you can; the CFPB says your rights depend on whether it was processed as an electronic transfer or as a check. FinCEN notes that thieves can also counterfeit new checks from the routing and account numbers on a stolen one, which is why the OCC suggests asking your bank about closing the account and opening a new one.
Report the theft to the Postal Inspection Service online or at 1-877-876-2455, and file a police report, keeping a copy for your bank, as the OCC suggests.
What IRIS can and can’t do when you pay by check
IRIS prints the PDF you upload and mails it to a US address by First-Class Mail. It can’t enclose a check, cash, or any other item you hold, so the check itself has to go in your own envelope.
What IRIS can mail is the paperwork around a payment: a cover letter explaining what the check is for, or a letter disputing a charge, from $3.20 for one black-and-white page. Certified Mail adds $6.95 for letters up to six sheets, with tracking on your order page. IRIS doesn’t offer Registered Mail.
Sources & further reading
Product details checked against the IRIS API contract when this article was published. Platform references can change; consult the linked documentation when implementing.
- FinCEN Alert FIN-2023-Alert003: Mail theft-related check fraud (Feb. 27, 2023)
- USPIS: Check washing
- USPIS: Mail and package theft
- USPIS: ABA and USPIS partnership to combat check fraud
- OCC: Check fraud
- OCC Safe Money: Check fraud (PDF)
- USPS: USPS and Postal Inspection Service expand crime prevention measures (May 12, 2023)
- CFPB: How do I stop payment on a check?
- CFPB: I discovered an unauthorized check written on my account
- USPS Domestic Mail Manual 503: Extra services
- USPS Notice 123: Price list
- USPIS: Report a crime
Published by IRIS Postal Forms, operated by Great Lakes Computing Office LLC. Send a correction.