How to File GSTR-1 Step by Step: Complete Guide 2025-26

GSTR-1 is one of the most fundamental GST returns in India. Every registered taxpayer who makes outward supplies of goods or services must file this return, declaring all their sales invoices for the month or quarter. Whether you are a monthly filer processing hundreds of B2B invoices or a small retailer filing quarterly under the QRMP scheme, understanding how to file GSTR-1 correctly is not just a compliance formality — it directly impacts your buyers’ ability to claim Input Tax Credit (ITC).

This is the most comprehensive, step-by-step guide on the GSTR-1 filing process for FY 2025-26.

What is GSTR-1?

GSTR-1 is an outward supply return. It is a detailed statement of all invoices raised by a GST-registered business during a given tax period (month or quarter). When you file GSTR-1, the information flows automatically into the GSTR-2B of all your registered buyers. This means your filing directly determines how much ITC your business partners can claim.

If you file GSTR-1 late, miss an invoice, or enter incorrect details, your buyers are directly affected. They either cannot claim ITC on that invoice, or they claim incorrect ITC and face penalties. This interdependence makes GSTR-1 filing a shared responsibility in the GST ecosystem.

Who Must File GSTR-1?

Every GST-registered taxpayer who makes outward taxable supplies must file GSTR-1. This includes:

• Regular taxpayers (monthly filers with turnover above ₹5 Crore)
• QRMP scheme taxpayers (quarterly filers with turnover up to ₹5 Crore)
• Casual Taxable Persons

The following are exempt from filing GSTR-1:

• Input Service Distributors (ISD) — they file GSTR-6 instead
• Non-Resident Taxable Persons — they file GSTR-5
• Composition scheme dealers — they file CMP-08 and GSTR-4

GSTR-1 Due Dates for FY 2025-26

Taxpayer Category	Period	Due Date
Monthly Filers (Turnover > ₹5 Cr)	Every Month	11th of the following month
Quarterly Filers (QRMP, Turnover ≤ ₹5 Cr)	Every Quarter	13th of the month after quarter-end

Important: Monthly filers must file GSTR-1 by the 11th of every month. So for June 2025 sales, you must file by 11 July 2025.

For QRMP filers (quarterly), the due dates are:

• Q1 (Apr-Jun): 13 July 2025
• Q2 (Jul-Sep): 13 October 2025
• Q3 (Oct-Dec): 13 January 2026
• Q4 (Jan-Mar): 13 April 2026

Step-by-Step: How to File GSTR-1 Online

Step 1: Login to the GST Portal

Go to gst.gov.in and log in with your GSTIN and password.

Step 2: Navigate to Returns Dashboard

Click on Services → Returns → Returns Dashboard. Select the relevant Financial Year and Return Filing Period, then click Search.

Step 3: Open GSTR-1

Under the “GSTR-1” tile, click the Prepare Online button. If you have more than 500 invoices, you may prefer to use the Prepare Offline option and upload a JSON file generated via accounting software.

Step 4: Fill B2B Invoices (Table 4A/4B/6B)

This is the most critical table. Enter all invoices you raised for GST-registered buyers (B2B). For each invoice, you need:

• Receiver’s GSTIN (15-digit)
• Invoice Number (must match exactly what you issued)
• Invoice Date
• Invoice Value (total including GST)
• Taxable Value
• Place of Supply (state code)
• Tax Rate (5%, 12%, 18%, 28%)
• IGST/CGST/SGST amount

Pro Tip: Always verify your buyer’s GSTIN before entering it using our GSTIN Validator. An invalid GSTIN will cause ITC mismatch issues.

Step 5: Fill B2C Large Invoices (Table 5A)

For invoices to unregistered buyers exceeding ₹2.5 Lakhs in value for interstate supplies, enter the full invoice details under Table 5 (B2CL - B2C Large).

Step 6: Fill B2C Small Summary (Table 7)

All other invoices to unregistered buyers (below ₹2.5 Lakhs, or all intra-state B2C invoices) are summarized in Table 7 (B2CS - B2C Small). You do not need to enter individual invoices here — just the aggregate taxable value and tax amount for each tax rate and state combination.

Step 7: Fill Export Invoices (Table 6A)

If you export goods or services, enter all export invoices here. Exports are zero-rated. You must mention whether the export was with payment of IGST or under LUT without payment of IGST.

Step 8: Fill Nil-Rated & Exempt Supply Details (Table 8)

Declare all transactions involving nil-rated (0% GST) or exempted goods and services. This includes agricultural produce, healthcare services, and educational services.

Step 9: HSN Summary (Table 12)

From April 2021, you must provide an HSN (Harmonized System of Nomenclature) summary. This is a table summarizing your sales by HSN/SAC code. The required digits depend on your turnover:

• Annual turnover up to ₹5 Crore: 4-digit HSN codes
• Annual turnover above ₹5 Crore: 6-digit HSN codes

Use our HSN Code Lookup tool to find the correct codes.

Step 10: Submit and File with DSC/EVC

Once all tables are filled, click Generate Summary. Review the auto-computed summary. If everything looks correct:

1. Click Submit GSTR-1
2. A confirmation popup will appear. Verify the details.
3. Sign using your DSC (Digital Signature Certificate) or EVC (Electronic Verification Code) sent to your registered mobile/email.

Your GSTR-1 is now filed!

How to File a Nil GSTR-1

If you had zero sales during the tax period, you must still file a Nil GSTR-1. You cannot skip filing even if there are no transactions.

For nil returns, the process is simpler:

1. Log in → Returns Dashboard → Select Period → GSTR-1 → Prepare Online.
2. Do not enter any data in any table.
3. Click Generate Summary → Submit → File.

Alternatively, for QRMP filers, nil GSTR-1 returns can be filed quickly via SMS. Send a message NIL R1 <GSTIN> <Tax Period (MMYYYY)> to 14409 from your registered mobile number.

Late Fees for GSTR-1

Filing GSTR-1 after the due date attracts a late fee. As per the latest government notifications:

• For returns with nil tax liability: ₹20 per day (₹10 CGST + ₹10 SGST), capped at ₹500.
• For all other returns: ₹50 per day (₹25 CGST + ₹25 SGST), capped at ₹10,000.

Use our GST Late Fee Calculator to calculate the exact penalty for any delay.

GSTR-1 Amendments: Correcting Mistakes

If you filed an invoice with wrong details (wrong GSTIN, wrong amount, wrong tax rate), you can amend it in the next period’s GSTR-1. Go to the amendment table (Table 9 for B2B, Table 10 for B2CL). You can amend invoices from any previous period, but you cannot amend an invoice from more than three years ago.

The amended invoice will flow into your buyer’s GSTR-2B for the month in which you file the amendment, not the original period.

Conclusion

Filing GSTR-1 accurately and on time is the foundation of GST compliance. Every invoice you file affects your buyers’ ITC, your standing with the tax department, and your business’s overall credibility. Set up a monthly calendar reminder for the 11th (or 13th for quarterly filers), and use good accounting software to automate invoice generation and upload.