Ind. Code § 6-8.1-8-1
However, if a tax liability payment is made by bank draft, check, cashier's check, or money order, the liability is not finally discharged and the person has not paid the tax until the draft, check, or money order has been honored by the institution on which it is drawn. If the payment is made by credit card, debit card, charge card, or similar method, the liability is not finally discharged and the person has not paid the tax until the department receives payment or credit from the institution responsible for making the payment or credit. The department may contract with a bank or credit card vendor for acceptance of bank or credit cards. However, if there is a vendor transaction charge or discount fee, whether billed to the department or charged directly to the department's account, the department or credit card vendor may collect from the person using the bank or credit card a fee that may not exceed the highest transaction charge or discount fee charged to the department by the bank or credit card vendor during the most recent collection period. This fee may be collected regardless of any agreement between the bank and a credit card vendor or regardless of any internal policy of the credit card vendor that may prohibit this type of fee. The fee is a permitted additional charge under IC 24-4.5-3-202.
IC 6-8.1-8-1