GSTR-1 Explained

GSTR-1 is the return you file to report all your outward supplies (sales). Every invoice you issue — whether to a registered business, an unregistered customer, or for exports — must appear in GSTR-1. Your buyers use this data to claim Input Tax Credit.

Who Must File GSTR-1?

Every registered person (except those under the Composition Scheme) must file GSTR-1. Even if you had no sales during a period, you must file a nil return. Non-filing attracts late fees of ₹50 per day (₹25 for nil returns), subject to a maximum of ₹10,000, plus interest at 18% per annum on the net tax liability.

Filing Frequency

Monthly Filers

Due on the 11th of the following month. Applicable if your aggregate turnover exceeds ₹5 crore in the previous year, or if you opted out of the QRMP scheme.

Quarterly Filers (QRMP)

Due on the 13th of the month following the quarter. Available to businesses with turnover up to ₹5 crore. Must use Invoice Furnishing Facility (IFF) for B2B invoices in the first two months of each quarter.

GSTR-1 Tables Explained

GSTR-1 has 13 tables. Not all tables apply to every taxpayer — you only need to fill in the tables relevant to your outward supplies.

Table 4A

B2B Invoices

All invoices issued to registered persons (B2B). Each invoice is reported with the recipient's GSTIN, invoice number, date, place of supply, and tax amounts. This is the primary source of ITC for your buyers.

Table 5

B2CL (Large Unregistered)

Invoices to unregistered persons (B2C) where the invoice value exceeds ₹2,50,000. Reported with place of supply, rate, and tax amounts. Includes inter-state B2C supplies above the threshold.

Table 7

B2CS (Small Unregistered)

All other B2C supplies — intra-state below ₹2,50,000, and inter-state below ₹2,50,000 that don't require individual invoice reporting. Aggregated by HSN code and rate.

Table 6

Exports and SEZ

Export invoices (with or without LUT/Bond), supplies to SEZ units/developers, and deemed exports. Requires shipping bill details and port codes.

Table 9B

Credit and Debit Notes

Credit notes issued to reduce the value of a previously reported invoice (returns, discounts, corrections). Debit notes to increase value. Must reference the original invoice.

Table 11

Advances Received

Advances received for future supply, reported with place of supply and tax rate. Must be adjusted when the actual invoice is issued in a subsequent period.

Table 8

Nil Rated / Exempt

Summary of nil-rated, exempt, and non-GST supplies. Even if all your supplies are nil-rated or exempt, you must file GSTR-1 with a nil declaration.

Table 12

HSN Summary

HSN-wise summary of all outward supplies. HSN codes must be reported at 4, 6, or 8 digits depending on your turnover. This table is auto-populated from the invoice data you enter.

Table 13

Documents Issued

Summary of documents issued during the period: invoices, credit notes, debit notes, delivery challans, and other documents. Used for reconciliation with the documents counter.

Common Errors and How to Avoid Them

Wrong GSTIN of recipient

Impact: Buyer cannot claim ITC because the invoice doesn't appear in their GSTR-2B.

Fix: Verify the recipient GSTIN using the GSTN portal search. Use the GSTIN validation tool on this site.

Incorrect place of supply

Impact: Wrong CGST+SGST vs. IGST classification. This affects the recipient's ITC claim and your tax liability.

Fix: Place of supply is determined by the nature of supply (goods: location at time of movement; services: location of recipient for B2B).

Invoice number duplication

Impact: GSTN rejects the invoice. Duplicate invoice numbers within a financial year are not allowed.

Fix: Ensure invoice numbers are sequential and unique within a financial year. Prefix with financial year if needed (e.g., INV/2024-25/001).

HSN code mismatch

Impact: May trigger mismatch notices. HSN summary must reconcile with invoice data.

Fix: Use the correct HSN code for your product. Check the GST rate finder on the GSTN portal.

Reporting in wrong tax period

Impact: Interest liability if tax is reported late. Credit notes in wrong period can increase tax liability.

Fix: Report invoices in the tax period where the supply was made (date of invoice, not date of filing).

Forgetting to report credit notes

Impact: Tax liability is overstated. Buyer's ITC may also be affected.

Fix: Issue and report credit notes in the same period as the original invoice if possible, or in the period the credit note was issued.

Prepare Your GSTR-1

Use GSTSelf to prepare and validate your GSTR-1 data before uploading to the GSTN portal. All processing happens in your browser — your invoice data never leaves your device.

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