Determination of unpaid tax triggers show cause notice requiring tax, interest and penalties with specified settlement windows. Determination of tax not paid, short paid, erroneously refunded, or input tax credit wrongly availed or utilised due to fraud or wilful misstatement or suppression of facts prompts a show cause notice requiring payment of tax, interest and a penalty equal to the tax. Taxpayers can preempt notice by voluntary payment with a reduced penalty, or conclude proceedings by paying specified reduced penalties within thirty days of notice or order. The proper officer issues an order after considering representations and within the statutory limitation periods; related procedural and definitional clarifications are provided.