Citibank, one of the major banks in the United States, sends a strong message: if you ignore a negative balance in your account, you can get yourself into serious trouble. The bank reminds its customers that keeping an insufficient balance can trigger multiple consequences.
It's a very clear warning, made so that thousands of users in the United States don't experience a problem in their financial lives. A negative balance occurs when you spend more money than you have in your checking account. It can happen because of an automatic payment, an unexpected charge, or a transfer.
What happens if your balance is negative and you do nothing: Citibank speaks clearly
Although Citibank eliminated many overdraft fees in 2022, they warn that this doesn't mean you can be careless without consequences. Your account goes negative and Citibank can decide to return the transactions instead of covering them. You lose access to your account and the problems begin.

Although Citibank eliminated some fees, they can still apply an "NSF fee" (non‑sufficient funds fee) if your account doesn't cover a payment. These charges vary, but the label is usually around $30 per failed transaction. In addition, if you let days go by, the bank could close your account.
You could be reported to ChexSystems, a database of defaulters, and another bank could deny you the ability to open an account in the future. Even if you pay later, that record remains for at least five years. You lose credibility with Citibank, and if you repeat incidents, the bank can cancel your services or ban you.
Citibank will make you pay if your balance is negative
Although they no longer charge the classic "overdraft fee," if you fail to pay a transaction, Citibank will charge you an NSF fee. In addition, your account can accrue interest on the negative balance, depending on the type of account you have.

To avoid problems, Citibank insists on activating low balance alerts and you'll receive notifications by email or app when your account gets close to zero. Link backup accounts; you can use a savings account or an overdraft protection plan. In case of a negative balance, the money is transferred automatically.
Additionally, monitor your account regularly. Review your charges and transactions, especially recurring payments. Don't wait for the bank's notifications.
Solution to the problem: how to react
If you see your account is negative, deposit money immediately; that's the only way to stop the fees. Contact Citibank through their app, website, or by calling the official number. Request to have possible NSF fees removed and arrange a payment plan.
Check your status in ChexSystems (it's a good idea to do this once the balance is settled). If you appear with a negative record, pay what's pending and request its correction.