Willful GST tax evasion triggers tiered imprisonment and fines, with certain invoice-related offences being cognizable and non-bailable. The section lists GST offences-invoice-related frauds, wrongful availment of input tax credit, failure to remit collected tax, falsification of records, obstruction, dealing with confiscable goods, tampering with evidence, supplying false information, and attempts or abetment-and prescribes tiered imprisonment and fines according to the quantum of tax evaded or wrongfully claimed. Certain offences are cognizable and non-bailable, others are non-cognizable and bailable; repeat convictions increase punishment; minimum imprisonment applies to specified tiers unless special reasons are recorded; prosecution requires prior sanction of the Commissioner; 'tax' includes evaded tax, wrongfully availed input tax credit and wrongfully taken refunds under GST enactments.