ACH transactions take 3-4 business days to be notified of success or failure. Once successful, it'll take another 1-2 business days to be paid out to your bank.
If the payment currently says pending, the transaction has not yet been approved. Once it changes to "Charged," it will take 1-2 business days to appear in your account.
When created, ACH charges will have the initial status of pending that is reflected in the Billing section of a project
Over the 3-4 day period, the payment will either transition to succeeded or failed, depending on your clients' bank.
Successful/Confirmed ACH payments will then be scheduled for automatic Outbound Transfer.
Your client will see the payment reflected on their bank statement 1-2 days after creating the charge. (Your customer will know the payment succeeded before the bank notifies Stripe.)
The payment will hit your account 1-2 days after succeeding.
Failures can happen for a number of reasons - insufficient funds, a bad account number, or the customer disabled debits from their bank account. You will be notified if a client's payment does fail.
ACH payments made before 7:00pm ET are eligible to be processed the same day.