GAS-1276, International Fuel Tax Agreement (IFTA) Return GAS-1276, International Fuel Tax Agreement (IFTA) Return - Use this form to file your original or amended tax return. Documents Gas-1276_3-24-24_Web_v1_Final.pdf Related Content Instructions - GAS-1276, International Fuel Tax Agreement (IFTA) Return GAS-1278, International Fuel Tax Agreement (IFTA) Fuel Tax Rates IFTA Annual Interest Rates