The deadline for filing to obtain a credit for an overpayment of Sales and Use Tax changes semiannually on January 1 and July 1. If you file Form ST-1-X between January 1 and June 30, you may file a claim for credit for the amounts you overpaid during the current year and previous 36 months. Beginning July 1, you may file a claim for the amounts you overpaid during the current year and previous 30 months.
Note: We use the postmark date to determine whether a properly amended return (i.e., claim for credit) has been timely filed.
If you are making an additional payment, there is no deadline; however, the longer you wait to pay, the more interest and, when applicable, penalty you will owe.