Hi @K_PS,

Allow me to join this conversation and clear things up on where you can find the ACH authorization form.

You'll have to create a recurring sales receipt template first to get a hold of the form. Let me show you how:

1. Go to the Gear icon, then select Recurring Transactions.
2. Click New.
3. From the Transaction Type drop-down box, select Sales Receipt, then OK.
4. Enter a Template Name.
5. From the Type drop-down box, select Scheduled.
6. Select the customer’s name from the Customer drop-down box. Then, verify the email.
   • Note: You can select Automatically send emails to send notifications to your customer when you process their payment.
7. Set the interval. For example, if you need a sales receipt every first day of the month, the interval is Monthly on day 1st of every 1 month.
8. Enter the Start and End Date.
9. From the Payment method drop-down box, select Check.
   • Note: Select the Authorization hyperlink to send the Bank Transfer Authorization form to your customer. Check the box to ensure the payment will process each time a form is created.
10. Select Save template.

After printing the authorization form, follow the steps listed on the link shared by @Mark-R above: Authorization form for recurring payments.

In case you'd like to know where you can get the authorization form for credit card billing, take a look at this article: Set up a recurring sales receipt.

Do you have any other questions in mind? Post them in the comments below, and I'll get back to you.