Do I need to maintain a minimum balance in my account?

There is no minimum balance required after the initial $10 deposit.

Sometimes more is more! (Side note: if your account is at $0 balance for several months, you may receive a friendly email asking if you are still interested in keeping the account open. Additionally, accounts with no customer initiated activity for 12 consecutive months will receive a notice before they reach what's called "dormant account" status).