Input tax credit extension permits late claims for specified past periods and for revoked registrations subject to time limits. The amendment adds transitional sub-sections to permit claim of input tax credit for invoices or debit notes from specified past years in returns filed up to a prescribed cut-off, and to permit claims after cancellation where cancellation is later revoked, subject to specified filing deadlines and the condition that availment was not restricted at the time of cancellation; it also provides that no refund is admissible where tax was paid or credit reversed.