Introduction

GST return filing in India involves multiple forms, but the two most critical monthly filings for regular taxpayers are GSTR-1 and GSTR-3B.
Understanding the difference between these two returns—and how they work together—is essential for accurate reporting, preventing mismatches, and avoiding interest or penalties.
This guide simplifies GSTR-1 and GSTR-3B filing, explains their individual roles, highlights key differences, and covers best practices for reconciliation.

What Is GSTR-1?

GSTR-1 is a statement of outward supplies filed by every registered taxpayer.

It contains:

• Invoice-wise details of B2B sales

• Summary of B2C sales

• Export invoices

• Credit/debit notes

• Amendments relating to previous periods

Purpose of GSTR-1

• Communicates outward supply data to the government

• Auto-populates invoices in recipients’ GSTR-2A/2B

• Enables claim of input tax credit (ITC) by buyers

• Forms the foundation for GST ecosystem data matching

Frequency

• Monthly for most taxpayers

• Quarterly under the QRMP scheme

What Is GSTR-3B?

GSTR-3B is a summary self-declaration return where taxpayers:

• Report total outward supply values

• Claim available input tax credit

• Discharge their monthly tax liability

It does not contain invoice-wise details—only consolidated values.

Purpose of GSTR-3B

• Enables tax payment for the period

• Ensures compliance even if invoice details are pending

• Acts as a summary of net tax payable

Frequency

• Filed monthly or quarterly depending on the taxpayer category.

What Is GSTR-3B?

Why Both Returns Must Match

Mismatch between GSTR-1 and GSTR-3B can lead to:

• Notices under Sections 73/74

• Automated system-generated demands

• ITC reversals

• Interest and penalty

Matching outward supplies in both returns ensures smooth GST compliance.

Common Mismatches & How to Avoid Them

1. Sales Shown in GSTR-1 but Not in GSTR-3B

This leads to underpayment of tax → interest chargeable.

Solution:

Reconcile monthly and adjust differences immediately.

2. Excess Liability Reported in GSTR-3B

This causes tax overpayment.

Solution:

Claim refund from excess cash ledger or adjust in next month’s return.

3. Credit/Debit Notes Missed

Omission impacts tax liability and buyer ITC.

Solution:

Include all adjustments in both returns for the same period.

4. Reporting Zero-rated Supplies Incorrectly

Exports or SEZ supplies often mismatch between returns.

Solution:

Maintain separate registers for zero-rated transactions.

Best Practices for GSTR-1 & GSTR-3B Reconciliation

• Reconcile outward supplies monthly before filing

• Match e-way bills with sales data

• Verify advances, export invoices, and debit/credit notes

• Check GSTR-2B before filing 3B for accurate ITC

• Maintain internal sales registers and automated GST software reports

• Respond promptly to mismatch notices

Conclusion

GSTR-1 and GSTR-3B serve different but interconnected purposes in GST compliance. While GSTR-1 ensures accurate reporting of outward supplies, GSTR-3B enables tax payment and summarised monthly reporting. Filing both accurately and reconciling them regularly helps avoid mismatches, interest, penalties, and system-generated notices.

Bisways Consulting Group provides expert assistance in GST return filing, reconciliation, mismatch resolution, and compliance management to ensure your business stays fully compliant.