How to File GSTR-1 in 2026: Step by Step Guide

GSTR-1 is a monthly or quarterly return that every registered GST taxpayer in India must file. It contains details of all outward supplies — meaning all the sales invoices, credit notes, debit notes, and advances received during the filing period. Your customers use your GSTR-1 data to claim input tax credit, so accuracy is critical.

Every business registered under GST must file GSTR-1, regardless of whether you had any sales during the period. If you had zero sales, you still file a nil return. The only exceptions are businesses under the composition scheme (they file CMP-08 instead) and Input Service Distributors (they file ISD returns).

Filing GSTR-1 correctly and on time is important for three reasons: your customers depend on it for their ITC claims, late filing attracts a penalty of Rs 50 per day (Rs 20 for nil returns), and consistent late filing can lead to your GST registration being suspended. We built the GSTR-1 report in myBillPlease to generate automatically from your invoices — so you always have filing-ready data without manual compilation.

This guide covers everything you need to know about GSTR-1 filing in 2026, including the step-by-step process on the GST portal, the invoice format requirements, due dates, nil return filing, and the new GSTR-1A amendment form. Use our free GST calculator to verify tax amounts before filing.

GSTR-1 has multiple tables, each for a different type of supply. Understanding which invoices go where is the most common source of filing errors. Here is a breakdown:

Table 4 — B2B Supplies: All invoices issued to GST-registered businesses. Each invoice must include the customer's GSTIN, invoice number, date, taxable value, and tax amounts (CGST, SGST, or IGST). This is the most important table because your customer's ITC depends on it.

Table 5 — B2C Large: Inter-state sales to unregistered persons where the invoice value exceeds Rs 2.5 lakh. These are reported invoice-wise with the Place of Supply (state code).

Table 7 — B2C Small: All remaining B2C sales — intra-state sales of any value and inter-state sales below Rs 2.5 lakh. These are reported as a consolidated summary by rate, not invoice-wise.

Table 9 — Credit and Debit Notes: Any credit notes (refunds, returns) or debit notes (additional charges) issued during the period. For B2B credit notes, you must include the original invoice reference.

Table 12 — HSN Summary: Aggregate summary of all supplies grouped by HSN code. Required for all businesses — 4-digit HSN for turnover up to Rs 5 crore, 6-digit for above. Use our HSN code directory to find the correct codes.

If you use myBillPlease, the GSTR-1 report auto-classifies your invoices into B2B, B2C Large, and B2C Small based on customer GSTIN and invoice amount. Download the Excel file and upload it to the portal — no manual sorting needed.

If you had no outward supplies during the filing period — no sales invoices, no credit notes, no advances — you must still file a nil GSTR-1. Skipping it attracts a late fee of Rs 20 per day up to Rs 500.

Filing a nil return is simple: log in to the GST portal, go to Returns Dashboard, select the period, click GSTR-1, and click the Nil Return button at the top. Confirm and file with EVC (electronic verification code via OTP). The entire process takes under 2 minutes.

Common scenario: a new business registers for GST in January but starts operations in March. For January and February, file nil GSTR-1 returns. From March onwards, file regular returns with your invoice data.

A rising search query is GSTR-1A — this is the new amendment return introduced in 2025. If you discover errors in a filed GSTR-1 (wrong invoice amount, missing invoice, wrong GSTIN), you can file GSTR-1A to correct them before the GSTR-3B for that period is filed. Previously, corrections had to wait until the next month's GSTR-1. GSTR-1A makes corrections faster and keeps your customer's ITC claims accurate.