ACH (Automated Clearing House)
A US bank-to-bank electronic transfer network, used for low-cost direct payments from a member's checking account.
ACH is the network that moves money directly between US bank accounts — the same rails behind direct deposit and online bill pay. For dues collection it's the cheapest method because it carries a low, flat processing cost instead of a percentage, so it's usually the least expensive way for members to pay larger amounts.