How do I open a supplemental savings account in Alliant Online Banking? Online banking makes it simple to open Supplemental Savings accounts. 1. At the bottom of the left column (under the listing of your Alliant accounts), click on "Open a new account." 2. On the "Open New Account" page, select "Supplemental Savings," then follow the prompts to name your account, add a joint owner if applicable, and fund the account. Note that you may choose to open a Supplemental Savings account with a $0 balance and add funds later. If you have questions about opening a new Supplemental Savings account, send us a secure message in online banking (click "Messages" at the top of any online banking page) or mobile banking (click the talk icon at the top left of the app, then select the "Send a secure message" button) or call us at 800-328-1935.