India GST Compliance for Multi-Entity Businesses: The Complete 2026 Guide

India GST compliance: the full picture

India's GST system is one of the most digitally integrated tax regimes in the world. For businesses above ₹5 crore annual aggregate turnover, B2B invoices must be registered on the Invoice Registration Portal (IRP) and carry a valid IRN (Invoice Reference Number) and QR code. GSTR-1 (outward supplies) and GSTR-3B (summary return and tax payment) are filed monthly or quarterly depending on turnover. TDS (Tax Deducted at Source) under GST applies to notified government entities and certain large entities. TCS (Tax Collected at Source) applies to e-commerce operators.

For businesses with multiple GSTINs — registered in more than one state — each GSTIN is a separate tax registration with its own filing calendar. A business with 5 state GSTINs and 20 transaction months per year has 100+ GST returns to file annually. Without a system designed for this, the compliance burden is enormous.

E-invoicing under IRP: how it works

E-invoicing under India's IRP does not mean the invoice is generated on the IRP. It means the invoice data is reported to the IRP and authenticated with an IRN and digital signature before the invoice is shared with the customer.

The flow: the business system generates the invoice → the invoice data is submitted to the IRP API in the GSTN-standard JSON format → the IRP validates the data against the GSTN supplier and recipient GSTINs → the IRP returns an IRN, a digitally signed QR code, and a signed invoice JSON → the business system embeds the QR code and IRN in the invoice document → the invoice is shared with the customer.

The IRP-issued QR code contains the supplier GSTIN, recipient GSTIN, invoice number, date, total value, and IRN — all verifiable by the recipient and GSTN.

For businesses using ERP systems without native IRP integration, a GSP (GST Suvidha Provider) acts as an intermediary. Native integration eliminates this layer and its associated cost and latency.

GSTR-1 and GSTR-3B: automation and reconciliation

GSTR-1 is the monthly or quarterly return of outward supplies. It must be filed by the 11th of the following month (monthly) or the 13th of the quarter (quarterly). Every B2B invoice issued during the period must appear in GSTR-1 with the correct GSTIN, invoice number, date, taxable value, tax rate, and tax amount.

GSTR-3B is the summary return filed by the 20th of the following month. It consolidates outward supply tax liability, ITC (Input Tax Credit) claimed, and the net tax payable.

The critical reconciliation is between GSTR-1 and GSTR-2B (the auto-populated ITC statement generated from suppliers' GSTR-1 filings). ITC can only be claimed if the supplier has filed their GSTR-1 correctly and the invoice appears in GSTR-2B. Mismatches — where a purchase invoice is in your books but not in GSTR-2B — require follow-up with the supplier.

A system that automates GSTR-1 population from posted invoices and generates the GSTR-2B reconciliation report reduces month-end compliance from days to hours.

Multi-GSTIN management from a single platform

For businesses with operations in multiple states, each state registration is a separate GSTIN with its own filing calendar and ITC pool. Cross-state supply — where goods or services move between a supplier and recipient in different states — attracts IGST (integrated GST) rather than CGST/SGST, and the GST treatment depends on the place of supply rules.

In a multi-entity, multi-GSTIN business, the ERP must track which GSTIN each transaction belongs to, apply the correct tax treatment (IGST vs CGST/SGST), maintain separate ITC ledgers per GSTIN, and support filing for each GSTIN independently.

Tafkiro supports unlimited GSTINs within a single platform instance, with consolidated reporting across all GSTINs and individual GSTN filing support for each registration.

TDS, TCS, and annual compliance

TDS under Income Tax and TDS under GST are separate obligations. Under Income Tax, TDS applies to specific payment categories (rent, professional fees, contractor payments, salaries) at notified rates. Under GST, TDS applies at 2% on payments above ₹2.5 lakh by specific government and notified entities.

TCS under Income Tax applies to specific receipt categories. TCS under GST applies to e-commerce operators at 1% on net taxable supplies.

For businesses subject to multiple TDS/TCS streams, the compliance calendar is dense: monthly TDS payment by the 7th, quarterly TDS return (26Q/24Q) by the 31st of the following month, annual TDS reconciliation (Form 26AS), and GST TDS return (GSTR-7) by the 10th of each month.

An integrated system that calculates TDS/TCS at the transaction level, generates payment challans, and pre-populates returns from posted transactions is the only practical way to manage this without a dedicated compliance team.