How do I find my account number? At Alliant, your account number is called your share ID. Your share ID is included in your new Member Welcome Package. If you’re an Alliant online banking user, you can also find your share ID in online banking by clicking the "Membership Number" link in the blue toolbar at the top of all of your account pages. Please note that once your membership application is accepted, it takes approximately 7-10 days before you receive your new Member Welcome Package in the mail.