Advance tax penalty under section 234C: increases to default percentages and Explanation expanded to include amounts payable. The amendment increases the default percentage thresholds used to compute advance tax instalment interest and substitutes higher percentage terms for the lower and higher thresholds, effective from the Act's stated commencement; it also expands the Explanation to include amounts 'or payable' in addition to 'paid,' with that insertion deemed effective from the earlier fiscal date specified.