Original sentence: It will charge the cardholder's credit or debit card.Underpayment allowance: If a registered card has insufficient funds to pay a fare, but the balance is greater than $0 and has sufficient funds to cover the minimum base fare, the cardholder can incur a negative balance for one trip for a fee of $0.25
Edited sentence: It will charge the cardholder's credit/debit card.Underpayment allowance: If a registered card has insufficient funds to pay a fare, but the balance is greater than $0 and has sufficient funds to cover the minimum base fare, the cardholder can incur a negative balance for one trip for a small fee (25 cents)