Interest on delayed tax payment: notified rates apply and accrue from the day after tax becomes due, including on excess ITC claims. A person failing to pay tax within the prescribed period must pay interest on the unpaid tax at a rate notified by the Government, calculated in the prescribed manner from the day after the tax was due. Separate interest applies where a taxable person makes an undue or excess input tax credit claim or undue or excess reduction in output tax liability, with interest payable on the undue or excess amount at a notified rate subject to prescribed calculation.