There is no limit to how many credit unions you can join, with almost every credit union having the policy that “once a member, always a member.” So even if you no longer bank with a certain credit union, you may find that credit union useful to you in the future, and you will still be a member when you return for new business. Joining multiple credit unions is a common strategy among those who want to maximize the rates they earn on each account type. For instance, retirees with a significant amount invested in CDs can be well served by holding certificates of different term lengths at different banks or credit unions.