SAN FRANCISCO (KGO) — The U.S. Postal Service has a warning if you still mail checks: thieves are stealing them, altering them and cashing them.

7 On Your Side previously investigated dozens of stolen Napa County tax payments. Now, the scam is hitting more Bay Area residents.

Postal inspectors say mail theft surged during the pandemic, when millions of unemployment and stimulus checks were mailed out. Thieves saw an opportunity — and the fraud hasn’t stopped.

“Beginning in 2020 and continuing in 2023, the Postal Service experienced a significant increase in theft from mail receptacles,” said Brendan Donahue, U.S. Chief Postal Inspector.

Postal officials warned Congress last summer: mail theft was on the rise.

“Shocking. I’m shocked. Now I can’t trust the mailbox,” San Francisco resident Kyung Cha Moon said.

“The trust, sending a physical check, is gone,” Kyung’s son, Mitchell Mun, also added.

It happened to Mitchell Mun and his mom. Thieves stole three of her checks from the mail.

“This is altered. This is fraud. This is forgery,” Mun said.

The tampering seemed obvious.

Kyung Cha Moon mailed a $118 check to the San Francisco Rent Board. Thieves stole it, tacked on their name and added $4,000 to the amount.

They also stole property tax payments for San Mateo and San Francisco counties, inserted their names and cashed them.

“I’m only going to hand-deliver, hand-deliver, so no trust in the post office anymore, period,” Moon said.

The check images show they were deposited into a credit union account.

“And then our bank’s trying to collect the money from their bank,” Mun said.

Their bank, BMO, recovered the money for two of her checks, but not the third.

“And then who’s stuck with it? It’s us,” Mun said.

South Bay resident Bob Dilfer has been hit three times in two years.

“I’ve had at least three negative experiences paying by check,” Dilfer said.

First, a thief stole his $100 check and wrote it for $6,000. Luckily, an alert bank manager stopped it.

Later, he mailed three checks to pay bills, but the checks never arrived. Sensing it was mail theft, he quickly stopped payment, avoiding any loss.

Then last fall, he mailed a check to the IRS. Eight months later, the IRS said it never received his money.

“‘Mr. Dilfer, you’re short X amount of dollars.’ I said, ‘No, no, no, no. I wrote you a check way back,'” Dilfer said.

He looked at the check image and discovered the check had been cashed, but not by the IRS.

“My heart fell into my stomach,” Dilfer said.

A stranger’s name appeared instead of the Department of the Treasury.

Later, a postal clerk told him how crooks likely got his check.

“Yeah, they pulled up to the dock there, just took this whole bin, loaded the trunk of the car and drove off,” Dilfer said.

The clerk said three men stole an entire bin of mail from a post office loading dock and drove away. The clerk gave Dilfer photos of the alleged getaway car.

Now banks are urging customers to pay bills online.

Dilfer is still mailing checks, just certified, and only inside the post office.

“Which is safer, you know? People hacking my computer or hacking my mail? So far, mail is losing,” he said.

After 7 On Your Side reached out, Dilfer got a letter from his bank, Fidelity, saying it replaced the money.

“Which was very nice,” Dilfer said.

Which brings us back to Mitchell and his mom.

“We even told the bank we’re going to ABC7 On Your Side,” Mun said.

7 On Your Side asked BMO about that third check, and soon after, the bank did refund the money — $5,137 — stating: “We immediately reviewed this matter and the case has been resolved as part of our regular process.”

“So that was unbelievable,” Mun said.

“So thank you so much Channel 7. I love Channel 7. Watching almost 60 years,” Kyung Cha Moon said.

Most banks give customers just 30 to 60 days to report check fraud. If you still write checks, experts recommend using an indelible gel pen and monitoring your account regularly to make sure your money ends up where it’s supposed to go.

Take a look at more stories and videos by 7 On Your Side.

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