GSTR-1 Filing in India: Step-by-Step Guide, Deadlines & Best Practices (2026)

Introduction

GSTR-1 is a key outward supply return that every registered GST taxpayer must file to report sales and outward supplies for a given tax period. Accurate GSTR-1 filing ensures that buyers receive correct Input Tax Credit (ITC), GST returns reconcile properly, and compliance notices are avoided.

This guide by The Tax Company explains everything about GSTR-1 filing including invoice reporting, due dates, formats, common mistakes, and expert compliance tips.

What is GSTR-1?

GSTR-1 is a monthly or quarterly return used to report details of outward supplies made during the tax period. It includes:

• B2B invoices
• B2C large invoices
• Export invoices
• Credit notes and debit notes
• Advances received

This return is filed electronically on the GST portal.

Who Must File GSTR-1?

The following categories of taxpayers are required to file GSTR-1:

✔ Regular taxable persons
✔ Composition taxpayers (in simplified format)
✔ Casual taxable persons
✔ Non-resident taxable persons

The filing frequency depends on turnover limits and applicable GST notifications.

GSTR-1 Filing Frequency and Due Dates

Regular Taxpayer with Turnover Above Threshold
Filing Frequency: Monthly
Due Date: 11th of the following month

Quarterly Filers with Turnover Within Threshold
Filing Frequency: Quarterly
Due Date: 13th of the month following the quarter

Composition Taxpayers
Filing Frequency: Quarterly
Due Date: 18th of the month following the quarter

Due dates are subject to changes as notified by GST authorities.

Section-Wise Details of GSTR-1

B2B Invoices (Table 3.1)

All outward supplies made to GST-registered buyers must be reported here. Details include GSTIN of recipient, invoice number, invoice value, taxable value, tax rate, and applicable IGST, CGST, and SGST.

B2C Large Invoices (Table 3.1B)

Invoices issued to unregistered persons where invoice value exceeds ₹2.5 lakh must be reported separately.

Export Invoices (Table 6A)

Exports of goods and services, whether with payment of tax or under LUT, are reported in this section.

Credit and Debit Notes (Tables 3.1C and 3.1D)

Any adjustments made to previously issued invoices must be disclosed through credit and debit notes.

Advances Received (Table 5)

Advances received for future supplies where invoice has not yet been issued must be reported here.

Nil Rated, Exempt, and Non-GST Supplies (Tables 6B and 6C)

Supplies that are exempt, nil rated, or outside the scope of GST are declared in this section.

How to File GSTR-1 Step by Step

Step 1: Login to GST Portal

Visit the GST portal and log in using your credentials.

Step 2: Access Returns Dashboard

Select the relevant tax period and choose GSTR-1 from the returns dashboard.

Step 3: Prepare Return Sections

Enter data under the following categories:

✔ B2B invoices
✔ B2C large invoices
✔ Export invoices
✔ Credit and debit notes
✔ Advances received
✔ Nil rated and exempt supplies

Step 4: Upload Invoice Data

Invoices can be added manually or uploaded in bulk using JSON files generated from accounting software.

Step 5: Review and Validate

Verify total values, tax calculations, and GSTIN details before submission.

Step 6: Submit and File Return

Click submit and file GSTR-1 using either EVC (OTP-based verification) or DSC (Digital Signature Certificate).

Reconciliation and Matching

Regular reconciliation with:

✔ Sales register
✔ Accounting software data
✔ Purchase and ITC records

helps minimize mismatches and reduces the risk of departmental notices.

Common Mistakes to Avoid

❌ Incorrect GSTIN entries
❌ Missing invoices or delayed reporting
❌ Wrong tax rate selection
❌ Duplicate invoice uploads
❌ Filing under incorrect tax period
❌ Excluding B2C large transactions

Amendments to Filed GSTR-1

If errors are identified after filing, amendments can be made in subsequent tax periods under the amendment tables such as:

✔ B2B amendment section
✔ Credit and debit note adjustment sections

Corrections are reflected in future returns.

Impact on Input Tax Credit and Compliance

Accurate GSTR-1 filing ensures:

✔ Correct ITC availability to buyers
✔ Reduced mismatch with GSTR-2A and GSTR-2B
✔ Lower risk of scrutiny and assessment

Penalties for Non-Filing or Late Filing

Failure to file GSTR-1 on time can result in:

• Late fees of ₹100 per day under CGST and ₹100 per day under SGST
• Interest on delayed tax payments
• Compliance notices and scrutiny
• ITC blockage for customers

Best Practices for Smooth GSTR-1 Filing

✔ Maintain organized sales records
✔ Use GST-compliant accounting software
✔ Perform monthly reconciliation before filing
✔ Track due dates using compliance calendars
✔ Seek professional guidance for complex transactions

How The Tax Company Helps You

The Tax Company provides end-to-end GSTR-1 compliance support including:

✔ Return preparation and filing
✔ Invoice and data reconciliation
✔ Pre-filing error checks
✔ Amendment support
✔ Compliance tracking and reminders
✔ Audit readiness assistance
✔ Dedicated expert support

We help ensure timely, accurate, and hassle-free GST compliance.

Frequently Asked Questions

What happens if GSTR-1 is filed late?
Late fees apply and buyers may face ITC mismatches.

Can past period GSTR-1 returns be filed later?
Yes, but pending returns must be filed sequentially along with applicable late fees.

How frequently is GSTR-1 filed?
Large taxpayers file monthly while small taxpayers file quarterly.

Does GSTR-1 affect GSTR-3B filing?
Yes, outward supply data reported in GSTR-1 impacts tax liability reported in GSTR-3B.

Conclusion

Accurate and timely GSTR-1 filing is critical for GST compliance and seamless flow of input tax credit within the GST ecosystem. With proper planning and professional support, businesses can avoid penalties, reduce errors, and maintain smooth tax operations.

For reliable GSTR-1 filing and comprehensive GST compliance services, connect with The Tax Company today.