Recovery of unpaid GST: enforcement methods, settlement options, and joint liability for unpaid or collected-but-not-remitted tax. Recovery of unpaid or short-paid GST distinguishes non-fraud cases under Section 73 with a three-year adjudication limit and limited penalties on timely voluntary payment, and fraud-related cases under Section 74 with a five-year limit and statutory pre- and post-notice penalty payment options. Separate rules allow unconstrained issuance of notices for tax collected but not deposited, and the statute prescribes multiple enforcement methods and joint-and-several liability for transferees, partners, directors, liquidators and agents.