Interest on delayed tax payment applies from the day after due date; government notified rates determine liability. Section 50 requires payment of interest on tax unpaid within the prescribed period, at a Government notified rate not exceeding eighteen per cent, calculated in the prescribed manner from the day after the tax was due. Separate interest applies where a person makes an undue or excess input tax credit claim under section 42(10) or undue reduction in output tax under section 43(10), payable at a Government notified rate not exceeding twenty four per cent on the undue amount.