ACH
The Automated Clearing House network — the US bank-to-bank system that moves direct deposits, autopay bills, and most person-to-person transfers.
ACH stands for Automated Clearing House. It is the underlying network US banks use to move money between accounts in batches, without paper checks or card rails. Payroll direct deposits, most autopay bills, tax refunds, and app-to-app transfers between banks all typically ride on ACH.
ACH is cheap and slow by design. Transactions are collected during the day and processed in scheduled batches, so a transfer initiated on a Monday afternoon may not appear in the receiving account until Tuesday or Wednesday. Same-day ACH exists, but standard ACH commonly takes one to three business days and does not run on weekends or federal holidays.
The slowness is why balances can look wrong across a transfer: money can leave one account before it lands in the other. It is also why refunds paid by ACH take a few days to reappear. Wires are faster and more expensive; ACH is the workhorse for routine flows.
Plumb is financial education, not financial, investment, tax, or legal advice.