Integrated Tax apportionment reporting requires prescribed monthly and annual forms for uncertain place of supply and unidentified suppliers. Apportionment of Integrated Tax collected where the place of supply cannot be determined or the taxable person making the supply is not identifiable is to be reported through the common portal in prescribed forms for each State and Union Territory. Monthly State-wise consolidated details are to be transmitted in FORM GST STL-4.01, while the list of registered persons from whom such tax has been collected is to be furnished in FORM GST STL-4.02. FORM GST STL-4.03 covers cases where the taxable person is not identifiable and is submitted annually in October.