Yes. For security and privacy purposes, your four-digit passcode is required to authenticate every Voice Banking session. This prevents anyone near your Alexa® device from being able to access your account information.
Keep in mind that if another person is nearby when you are using this skill they may be able to overhear you interacting with Alexa and learn information about your accounts.
Alexa is a trademark of Amazon.com, Inc. or its affiliates.