An overdraft fee of $30 charged on January 8th likely happened because a transaction on your account caused your balance to go below zero, meaning you spent more money than you had available. Banks often allow such transactions to go through but then charge an overdraft fee as a cost for covering the shortfall temporarily. You would need to pay back the negative balance plus this fee to bring your account back to a positive balance.

Overdraft fees are common when:

• You use your debit card, write a check, or pay a bill that costs more than the amount in your account.
• The bank covers the transaction to avoid it being declined.
• Your account balance ends up negative, triggering the fee.

This fee is separate from non-sufficient funds (NSF) fees, which occur if a transaction is declined outright due to insufficient funds. Overdraft fees usually range from $15 to $37 depending on the bank.

In summary, the $30 overdraft fee occurred because one or more transactions on January 8th overdrew your account, and the bank charged this fee for providing that temporary overdraft loan.