California's Unclaimed Property Law stipulates that the balance of accounts with no activity for the last three years be remitted to the state controller's office as abandoned property.  If you do not deposit to, withdraw from, or show a personal interest in your credit union account, the balance will become unclaimed property and will be escheated to the state.  In order to prevent escheatment, you must show a continuing interest by making a deposit to or withdrawal from your account.