Tex. Transp. Code § 501.177

If, for any reason, the payment of a fee under this chapter by electronic funds transfer, credit card, or debit card is not honored by the funding institution, or by the electronic funds transfer, credit card, or debit card company on which the funds are drawn, the department may collect from the person who owes the fee being collected a service charge that is for the collection of that original amount and is in addition to the original fee. The amount of the service charge must be reasonably related to the expense incurred by the department in collecting the original amount.