Understanding ACH Scams: A Basic Overview

We kick off 2026 by getting right to the heart of your organization’s security vulnerabilities and the path for navigating through these network dangers and into safety. High on your list of “need-to-know” cyber crimes should be ACH Scams!

The Automated Clearing House (ACH) network is a system in the United States that processes electronic payments, such as direct deposits for payroll, bill payments, and transfers between bank accounts. Managed by Nacha, it handles billions of transactions annually, making everyday financial tasks efficient and cost-effective. Unfortunately, this convenience also creates opportunities for fraud.

ACH scams, or ACH fraud, involve unauthorized or deceptive use of the ACH network to steal funds. Fraudsters typically exploit the system's reliance on just a bank account number and routing number—information often printed on checks or shared legitimately—to initiate transfers without permission. Unlike credit card fraud, ACH transactions can be harder to reverse quickly due to processing delays.

To cyber criminals, these simple delays are enticing opportunities to “get away with it.”
Common ways scammers obtain bank account and routing number information include phishing emails that trick victims into revealing details, malware that steals data from devices, data breaches where account info is sold on the dark web, or social engineering tactics that manipulate people into providing credentials. Once armed with the details, fraudsters can pull funds (debits) or push fraudulent payments (credits).

One prevalent type is unauthorized debits, where scammers directly withdraw money from a victim's account, often in small amounts to avoid immediate detection. You don’t want this! Another is business email compromise (BEC), where fraudsters impersonate executives or vendors via email, urging urgent ACH payments to fake accounts. For example, an employee might receive a spoofed message from the "CEO" requesting a transfer for a "confidential deal."

If you receive urgent financial directives from your CEO via email, be very, very cautious!!

Vendor impersonation is also common: Scammers send forged invoices with altered bank details, tricking businesses into sending payments to fraudulent accounts. Payroll diversion scams involve posing as employees to redirect direct deposits. In one real-world case, a healthcare company lost hundreds of thousands when a hacker impersonated an employee and changed ACH instructions.

These scams often succeed due to the ACH network's batch processing, which can take one to two days to settle, giving fraudsters time to move money before detection. Reports indicate ACH fraud incidents are rising, with many businesses affected by debit or credit fraud in recent years.

To protect against ACH scams, individuals and businesses should use strong security practices: enable multi-factor authentication on banking accounts, verify payment changes via phone (not email), monitor accounts daily for unusual activity, and educate employees on recognizing phishing. Banks offer tools like ACH blocks or positive pay services to approve transactions manually, adding an extra layer of defense. Staying vigilant is key to minimizing risks in this evolving threat landscape.

Education is so important in the fight against cybercrime, and this is why we are offering more security training opportunities in 2026 than ever before. If you would like to learn more about how Promethius can help train your staff on best practices, please reach out to info@promethius.com.