Input Tax Credit reconciliation: procedures to verify ITC claimed in GSTR 3B when not reflected in GSTR 2A, including documentary proof requirements. Procedure to resolve differences between ITC claimed in FORM GSTR 3B and ITC appearing in FORM GSTR 2A for FY 2017 18 and 2018 19: proper officers must obtain invoice details and verify Section 16 eligibility (possession of tax invoice, receipt of goods/services, payment to supplier), check reversals under Sections 17/18 and timeliness under Section 16(4). To verify supplier tax payment, higher-value discrepancies require a CA/CMA certificate with UDIN, while lower-value discrepancies may be substantiated by a supplier declaration. Guidance applies to bona fide errors and ongoing proceedings only.