10 GST Changes from April 1, 2026: E-Invoicing, IMS, HSNS Cess, and Your FY 2026-27 Compliance Checklist

Why This Matters Now

FY 2026-27 has begun, and a wave of GST compliance changes took effect on April 1, 2026. From mandatory e-invoicing for a wider pool of businesses to the replacement of the GST Compensation Cess with the HSNS Cess, these changes affect invoicing, ITC claims, return filing, and export procedures. Whether you run a Rs 5 crore turnover business or manage GST compliance for multiple clients, here are the 10 changes you need to act on immediately.

1. E-Invoicing Now Mandatory for Rs 5 Crore+ Turnover

E-invoicing under GST is now mandatory for all businesses whose aggregate annual turnover (AATO) exceeded Rs 5 crore in any financial year from FY 2017-18 onwards. If your business crossed this threshold in FY 2025-26, you must generate e-invoices through the Invoice Registration Portal (IRP) for every B2B supply from April 1, 2026.

Action: Register on the IRP portal, integrate your billing software with the e-invoice API, and ensure every B2B invoice carries a valid IRN (Invoice Reference Number) before dispatch.

2. 30-Day E-Invoice Reporting Deadline for Rs 10 Crore+ Businesses

For businesses with AATO of Rs 10 crore and above, each invoice must be reported on the IRP within 30 days of the invoice date, effective April 1, 2026. Invoices reported after this 30-day window will be rejected by the portal, and ITC claims by the recipient on such invoices may be denied.

Action: Set up daily or weekly e-invoice reporting routines. Do not batch invoices at month-end. Late reporting is no longer just a compliance gap; it is a financial risk for your buyers.

3. Invoice Management System (IMS) Is Now Active

The GST Invoice Management System (IMS), introduced on the GST portal, now requires recipients to actively accept, reject, or keep pending the invoices reported by their suppliers. IMS data feeds directly into GSTR-2B auto-population. A credit note rejected in IMS creates additional GSTR-3B liability for the supplier.

Action: Log into the GST portal regularly (at least weekly) to review and take action on invoices in IMS. Ignoring IMS means your auto-populated GSTR-2B may not reflect your actual ITC position.

4. GST Compensation Cess Replaced by HSNS Cess on Tobacco and Pan Masala

The GST Compensation Cess, originally introduced in 2017 to compensate states for GST revenue shortfalls, expired on March 31, 2026. For tobacco products, pan masala, and aerated beverages, the cess has been replaced by the Health Security se National Security (HSNS) Cess under the HSNS Cess Act, 2025.

Key compliance differences under HSNS Cess:

• Registration is mandatory from February 1, 2026, with machine-wise declarations
• Monthly cess payment is due by the 7th of the following month
• Return filing is due by the 20th of the following month
• Track and trace mechanism (Section 148A, CGST Act) applies to notified goods

Action: If you deal in tobacco, pan masala, or aerated beverages, ensure HSNS Cess registration is complete and invoicing systems are updated to reflect the new cess instead of Compensation Cess from April 1, 2026.

5. Export Refund: Rs 1,000 Minimum Threshold Removed

Previously, GST provisions blocked refund claims below Rs 1,000 under Section 54 of the CGST Act. This minimum threshold has been removed effective April 1, 2026. All valid refund claims, regardless of amount, can now be processed.

Action: If you had accumulated small refund claims that were individually below Rs 1,000, you can now file them. Review pending refund amounts and consolidate claims for FY 2025-26 if applicable.

6. LUT Filing Required Before First Export Invoice of FY 2026-27

Exporters making zero-rated supplies without payment of IGST must file a fresh Letter of Undertaking (LUT) in Form GST RFD-11 for FY 2026-27 before generating any export invoice. The LUT from FY 2025-26 expired on March 31, 2026.

Action: File your LUT on the GST portal immediately if you have not already done so. Export invoices generated without a valid LUT will attract IGST, creating cash flow complications.

7. New Document Series Required from April 1

All enterprises must start a fresh document series from April 1, 2026, for invoices, debit notes, and credit notes. The numbering must restart or follow a new sequential series for FY 2026-27. This is a standard year-start requirement but carries penalties if not followed, as duplicate or out-of-sequence numbering triggers scrutiny.

Action: Verify that your accounting software and ERP systems have rolled over to the new FY 2026-27 document series. Cross-check the first few invoices to confirm sequential numbering.

8. GSTR-3B Hard Validations on the Portal

The GST portal has implemented hard validations that block GSTR-3B filing when there are significant mismatches between GSTR-1 (outward supplies) and GSTR-3B (summary return). Previously, these were advisory warnings. From FY 2026-27, certain mismatches will prevent filing entirely until resolved.

Additionally, a statutory 3-year time bar is now embedded within the CGST Act. Late filing of GSTR-3B beyond the 3-year window from the due date is no longer permitted on the portal.

Action: Reconcile GSTR-1 and GSTR-3B before filing. Address any auto-populated mismatches flagged by IMS. If you have any GSTR-3B returns pending from FY 2022-23 or earlier, file them immediately before they become permanently blocked.

9. Simplified Registration Withdrawal (Form REG-32)

Before April 1, 2026, a taxpayer wishing to withdraw their GST registration cancellation application needed to have filed returns for at least 3 months. From April 1, 2026, filing returns for just 1 complete tax period is sufficient to apply for withdrawal via Form REG-32.

Action: If your client’s GST registration was cancelled and they wish to revive it, the compliance burden for withdrawal is now lower. File one month’s returns and apply for REG-32.

10. Track and Trace Mechanism: Penalties Under Section 122B

The track and trace mechanism under Section 148A of the CGST Act, introduced by the Finance Act, 2025, requires unique identification markings on specified goods. Non-compliance attracts penalties under the newly inserted Section 122B: Rs 1,00,000 or 10% of the tax payable on such goods, whichever is higher.

While the list of notified goods is currently limited (primarily tobacco and pan masala), the framework is designed to expand. Businesses in notified sectors must invest in track and trace infrastructure.

Action: Check if your goods fall under the notified list. If yes, implement the required unique identification marking systems and maintain digital traceability records as prescribed.

Quick-Reference Compliance Checklist for April 2026

Item	Deadline	Who Must Act
File LUT for FY 2026-27 (Form RFD-11)	Before first export invoice	All exporters
Start new document series	April 1, 2026	All taxpayers
E-invoicing setup (Rs 5 crore+ AATO)	April 1, 2026	Newly covered businesses
HSNS Cess registration and compliance	Ongoing (registration from Feb 1, 2026)	Tobacco, pan masala, aerated beverages
IMS review and action	Before GSTR-3B filing each month	All taxpayers
GSTR-3B reconciliation	Before filing each month	All taxpayers
Pending GSTR-3B from FY 2022-23	Immediately (3-year bar applies)	Defaulters

Confused about how these GST changes affect your specific business? The compliance advisory team at A S Banka Advisors Private Limited helps businesses and CAs navigate GST transitions smoothly. Get expert guidance for your FY 2026-27 GST compliance setup.

Disclaimer: This article is for informational purposes only and does not constitute legal, tax, or financial advice. GST rules and thresholds are subject to change through subsequent CBIC notifications. Please consult a qualified professional for advice specific to your situation. Information is current as of April 7, 2026.