ACH transfers work by grouping transfers between banks. Once placed, the bank checks and sends transactions in batches. ACH offers businesses free or low-cost transfers, even for high volumes. ACH transfers are an easy way to manage bulk payments, and payroll, for example, with lower transaction costs when compared with other networks, such as credit or debit cards. And unlike most wire transfers, ACH transfers can be reversed in cases of fraud or payment error, offering senders more safety.