How to File
These are filed quarterly and are due at the end of the month following the end of the quarter (for example, January - March return is due April 30). If the end of the month falls on a holiday or weekend, the report is due on the next business day. A tax return is required even if a truck is not operated during a quarter.
Penalty and interest will be due if the tax return or payment is not postmarked by the due date. The late penalty is $50 or 10% of the tax due, whichever is greater. Interest is calculated only on a jurisdiction where tax is due.
Starting July 1, 2013, the interest charged for IFTA late payments will be two (2) percentage points above the underpayment rate established under Section 6621(a)(2) of the Internal Revenue Code. For the months of July 2013 through December 2014, the IFTA annual rate will be 5%. The monthly rate is 1/12 of this rate, or .4167%.
To calculate interest on a late filed or amended return, multiply the tax due in Column 10 using the following rules:
For example, if a return was due April 30, 2013 and was filed August 30, 2013, interest for the months of May and June would be calculated at 1% per month and the interest for July and August would be calculated at .4167% per month.