An Automated Clearing House, or ACH, withdrawal on a checking account is an electronic money transfer, authorizing a merchant to be paid for products or services, according to the U.S. Consumer Financial Protection Bureau. ACH charges are often used when paying bills directly from a bank account.
A consumer typically has to provide his bank account number and routing number to allow ACH withdrawal charges, the CFPB states. If the account doesn't have funds, the ACH charge may be returned automatically.
The ACH network enables fast, safe payment processing between banking institutions by organizing transactions into batches and sending the data to destination accounts electronically, according to the National Automated Clearing House Association. ACH can be used for direct deposit or direct payment, and NACHA rules require banks to settle the accounts and transfer any owed funds within two business days.