Contact your bank for a power of attorney form. You can write a letter, sign it and hand it to a bank professional.They will accept the letter but, may still have you sign their form. Learn how to write an effective authorization letter for bank withdrawal and ensure smooth transactions. Get tips and examples now! Please be advised that. Do you know how to find out if you are a beneficiary on a bank account? Upon receiving your completed form and voided check, CCF may call for verification. Sample Authorization Letter — ACH Transfer. Here we share Authorization letter to bank to Transaction, Collect Document, Withdraw Money, Wrong Transaction, Withdraw money, etc.