Reconciliation of turnover and ITC: GSTR-9C mandates itemised reconciliation, auditor certification and settlement of additional tax liabilities. Form GSTR-9C requires GSTIN-level reconciliation of audited annual financial statements with the GSTR-9 annual return through specified Parts: reconciliation of gross and taxable turnover (with enumerated adjustments and reasons for unreconciled differences), rate-wise reconciliation of tax liability and payments (including interest, late fee and penalty), and reconciliation of Input Tax Credit by expense head. The auditor must recommend and certify any additional liability, annex the audit report and financial statements, and the taxpayer must verify and settle amounts via prescribed electronic payment procedures.