Apportionment of integrated tax governs distribution of tax, interest and penalties across States, Union territories and the Central Government. Apportionment of integrated tax is provided for specified inter-State and import supplies where tax is paid to the Central Government, including cases involving unregistered persons, composition taxpayers, ineligible input tax credit, or failure to avail credit within the prescribed period. The balance integrated tax is then distributed to the State where the supply takes place or to the Central Government for Union territories, with fallback proportional rules where the place of supply or the taxable person cannot be separately identified. The same framework applies to interest, penalty, and compounding amount, and later refunds are adjusted against future apportionment.