Rule 46(b) requires a fresh, unique, sequential invoice series for each financial year, per GSTIN. Confirm the client's billing system actually reset to a new series from 1 April 2026 — a carried-over series is a common early-year finding that then contaminates GSTR-1 and e-invoice matching for the whole year. Verify before the first month-end close, not at year-end audit.
A LUT filed for FY 2025-26 expired on 31 March 2026 and does not carry forward. Any business exporting goods or services (or supplying to an SEZ) without payment of IGST must file a fresh LUT for FY 2026-27 BEFORE raising the first zero-rated invoice of the year — an export invoice raised without a current LUT on file forces IGST payment with a subsequent refund claim instead of the zero-rated route. Confirm the LUT acknowledgement (ARN) is on file before testing any export transaction.
Input tax credit on invoices/debit notes dated in FY 2025-26 must be claimed by the EARLIER of 30 November 2026 or the date the FY 2025-26 annual return (GSTR-9) is actually filed. Filing GSTR-9 early closes the window early — a client who files GSTR-9 in August 2026 loses the ability to claim missed FY 2025-26 ITC in September-November, even though the calendar cutoff hasn't arrived. Reconcile GSTR-2B against the purchase register well before the annual return is filed, not after.
A business whose aggregate turnover first crossed ₹5 crore during FY 2025-26 becomes mandatorily subject to e-invoicing from 1 April 2026 onward (the ₹5 Cr threshold itself has applied since August 2023 — this is about a specific business crossing it for the first time). Check the FY 2025-26 turnover figure early in the audit and flag any client approaching or newly past ₹5 crore for e-invoicing readiness — see the e-invoicing audit guide for the ongoing compliance procedures once onboarded.
The Invoice Management System governs whether inward supplies flow into GSTR-2B and eligible ITC. Deemed-acceptance and pending-item ageing rules mean an unattended IMS queue silently changes ITC outcomes — start-of-year is the right time to confirm the client has an actual IMS review cadence in place, not just react to it at return-filing time. See the IMS reconciliation guide for the full accept/reject/pending mechanics.
Facts verified 19 July 2026 against the CGST Act and Rules — Sec 16(4)'s 30 November cutoff and Rule 46(b)'s invoice-series reset are stable, recurring provisions; re-verify the LUT filing window and any e-invoicing threshold notification each year before reusing this checklist.
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Yes — Rule 46(b) of the CGST Rules requires a consistent, sequential, and unique invoice number series for each financial year at the GSTIN level. Businesses commonly get this wrong by continuing a prior year's numbering or by having multiple billing systems generate overlapping numbers; either creates reconciliation problems when GSTR-1, e-invoice and e-way bill records are cross-checked.
The LUT route (export without payment of IGST) is only available while a valid LUT is on file for that financial year. A LUT filed for FY 2025-26 expired 31 March 2026 and does not automatically extend. An export invoice raised in FY 2026-27 before the new LUT is filed technically requires IGST payment upfront, with the exporter then claiming a refund — an avoidable cash-flow and compliance cost if the LUT renewal is simply filed on time (recommended: within the first few days of April).
The earlier of 30 November 2026, or the date the FY 2025-26 annual return (GSTR-9) is actually filed — under Section 16(4) of the CGST Act. If the annual return is filed before 30 November, that earlier filing date becomes the effective cutoff for claiming any missed credit, so reconciling GSTR-2B against the purchase register should be substantially complete well before the annual return is filed, not treated as a year-end afterthought.
