Overview

If you still write checks — and many of our customers do — this page is for you. Check washing is one of the oldest forms of bank fraud, and unfortunately it’s made a comeback in recent years due to an increase in mail theft across the country.

The good news is that a few simple habits can make it very difficult for criminals to tamper with your checks. This guide explains what check washing is, how to spot it, and exactly what you can do to protect yourself.

What Is Check Washing?

Check washing happens when a criminal steals a check — usually from your mailbox — and uses common household chemicals to erase the ink. Once the ink is removed, they rewrite the check to themselves, often for a much larger amount, while leaving your signature intact.

Because your real signature is still on the check, it can be difficult for the bank to catch. By the time you notice something is wrong, the money may already be gone.

Did you know? Mail theft has increased significantly in recent years. Criminals sometimes steal keys directly from postal workers to access entire neighborhoods’ worth of mail at once. It’s not just a big-city problem — it happens in communities like ours too.

Use a Gel Ink Pen — It’s the Single Best Thing You Can Do

This one tip alone can dramatically reduce your risk. Gel ink pens — the kind with thick, smooth ink — bond deeply into the paper fibers in a way that makes the ink nearly impossible to wash out chemically.

Regular ballpoint pens and felt-tip markers sit on top of the paper and are much easier for criminals to remove.

• Look for pens labeled “gel ink” at any office supply or grocery store. Brands like Pilot G2 or Uni-ball are widely available and inexpensive.
• Keep one near your checkbook so it’s always handy.
• Press firmly when writing — the deeper the ink, the harder it is to tamper with.

Mail Your Checks Safely

Stealing outgoing mail from home mailboxes is one of the most common ways criminals get checks. A few simple changes to how you mail checks can make a big difference.

• Drop checks at the post office directly, at the counter or in a collection box inside the building. This is the safest option.
• Never leave outgoing mail in your home mailbox with the flag up, especially overnight or over a weekend. That raised flag is an open invitation.
• Mail checks early in the day so they’re collected quickly rather than sitting in a street-side box for hours.
• Consider switching to online bill pay for regular bills. It eliminates the need to mail checks entirely and is available through your Bank of Marin online banking account.

Fill Out Your Checks Carefully

How you write a check matters. A few small habits make it harder for anyone to alter the information.

• Write the full name of the payee — avoid abbreviations or leaving the payee line blank.
• Draw a line through any blank space after the payee name and after the written dollar amount. This prevents anyone from adding words or numbers.
• Write the dollar amount as close to the left edge as possible, leaving no room for extra digits to be inserted in front.
• Keep a record of every check you write — the check number, date, payee, and amount. This makes it easier to spot anything unusual.

Monitor Your Account Regularly

Catching a problem early is the next best thing to preventing it. Most check washing victims don’t notice until weeks later — by then, recovering the funds can be much harder.

• Review your bank statements frequently, even just a quick check once a week. Look for any checks that cleared that you don’t recognize.
• Set up account alerts through Bank of Marin online banking to notify you any time a check clears above a certain dollar amount.
• Sign up for USPS Informed Delivery (free at informeddelivery.usps.com). Each morning, you’ll receive an email with photos of the mail scheduled to arrive that day — a handy way to notice if something expected never shows up.

If something looks wrong on your statement, don’t wait. Call us right away at (866) 626-6004. The sooner you report it, the better your chances of resolving it.

What to Do If You Think You’ve Been a Victim

If you notice a check on your statement that you don’t recognize — or if the amount or payee on a cleared check doesn’t match what you wrote — take these steps right away:

• Call Bank of Marin immediately at (866) 626-6004 to report the suspicious transaction.
• File a report with your local post office if you believe your mail was stolen — they take this seriously and can investigate.
• File a complaint with the U.S. Postal Inspection Service at postalinspectors.uspis.gov, which investigates mail theft nationwide.
• Consider placing a fraud alert on your credit report with one of the three major credit bureaus (Equifax, Experian, or TransUnion).

Need Help?

If you’re ever unsure about a check, a transaction on your statement, or anything related to your Bank of Marin account, please don’t hesitate to call us at (866) 626-6004 or visit a branch in person. We’re always happy to take a look with you.

Remember: When in doubt, do not give out information or send money — contact your bank first!