If you have questions about ACH Credit, we ask that you please call 217-782-6257 so that our staff can educate you about this payment option beforehand. A bank letter is an official document from your bank that provides important information about your business' official bank account.The first step in using an ACH authorization form is to request this form from your bank or financial institution. Please make sure you send us the following… This completed form. Include your voided check or bank letter. Letter of confirmation will be mailed to you upon completion of ACH set up. Authorized Signature: Date: Page 2. Enroll customers in lobby, batch and submit ENR enrollments through ACH from the financial institution. We will cover how to properly fill out an ACH form and how to submit the additional information required. If not: Complete a direct deposit form.