If you are registered under GST, you are required to file multiple returns each month or quarter. The two most common and frequently confused returns are GSTR-1 and GSTR-3B. Understanding the difference between these two returns is essential to avoid penalties, interest charges, and GST notices.

This guide explains GSTR-1 and GSTR-3B in plain language — what each reports, who has to file them, their due dates, and the consequences of filing them incorrectly.

What is GSTR-1?

GSTR-1 is a monthly or quarterly return that captures details of all outward supplies (sales) made by a registered taxpayer. It is essentially your sales register submitted to the GST portal. Once you file GSTR-1, the details auto-populate in your buyers’ GSTR-2B, allowing them to claim Input Tax Credit (ITC).

Key points about GSTR-1:

• Reports all B2B invoices, B2C invoices, credit notes, debit notes, and export invoices
• Does not involve any tax payment
• Acts as the foundation for your buyer’s ITC claims
• Errors in GSTR-1 can cause ITC mismatch issues for your customers

What is GSTR-3B?

GSTR-3B is a monthly self-assessment return where you declare your net GST liability for the period and make the actual tax payment. It is a summary return, not an invoice-level return. GSTR-3B must be filed every month by all regular GST taxpayers, regardless of whether they have transactions or not.

Key points about GSTR-3B:

• Reports total outward supplies, inward supplies (ITC), and net tax payable
• Tax payment is made while filing GSTR-3B
• Even if there are nil transactions, a nil GSTR-3B must be filed
• Late filing attracts interest at 18% per annum on outstanding tax and a late fee

GSTR-1 vs GSTR-3B: Side-by-Side Comparison

• Purpose — GSTR-1: Report outward supplies (sales); GSTR-3B: Report and pay net GST liability
• Invoice-level detail — GSTR-1: Yes, every invoice separately; GSTR-3B: No, consolidated summary only
• Tax payment — GSTR-1: No payment; GSTR-3B: Tax payment mandatory
• ITC claim — GSTR-1: Not applicable; GSTR-3B: ITC is claimed here
• Who must file — GSTR-1: All regular taxpayers; GSTR-3B: All regular taxpayers
• Frequency — GSTR-1: Monthly (large) / Quarterly (QRMP scheme); GSTR-3B: Always monthly

Due Dates for GSTR-1 and GSTR-3B in 2026

GSTR-1 Due Dates

• Monthly filers (turnover above ₹5 crore): 11th of the following month
• Quarterly filers under QRMP scheme (turnover up to ₹5 crore): 13th of the month following the quarter
• IFF (Invoice Furnishing Facility) for QRMP taxpayers: 13th of the first two months of the quarter

GSTR-3B Due Dates

• Category 1 (Turnover above ₹5 crore or any state): 20th of the following month
• Category 2 (Turnover up to ₹5 crore, certain states): 22nd of the following month
• Category 3 (Turnover up to ₹5 crore, other states): 24th of the following month

Important: Always file GSTR-1 before GSTR-3B. GSTR-1 data feeds into GSTR-2B, which in turn is used to verify ITC while filing GSTR-3B.

What Happens If GSTR-1 and GSTR-3B Data Don’t Match?

A mismatch between GSTR-1 and GSTR-3B is a red flag for GST authorities. Common consequences:

• GST department issues a notice under GSTR-3A for unexplained differences
• ITC claimed in GSTR-3B but not reflected in GSTR-2B can be disallowed
• Excess ITC claimed (claimed more than eligible) triggers a demand notice with interest and penalty
• Consistent mismatches can trigger a GST audit

To avoid mismatches: Reconcile GSTR-1 data with your books of accounts before filing. Reconcile GSTR-2B with your purchase register before claiming ITC in GSTR-3B.

Late Fees for GSTR-1 and GSTR-3B

• GSTR-1 late fee: ₹50 per day (₹25 CGST + ₹25 SGST); ₹20 per day for nil returns
• GSTR-3B late fee: ₹50 per day (₹25 CGST + ₹25 SGST); ₹20 per day for nil returns
• Interest on late tax payment (GSTR-3B): 18% per annum on the outstanding tax amount from the due date
• Maximum late fee for GSTR-1 and GSTR-3B: Capped at ₹10,000 per return under the GST Amnesty schemes

What is the QRMP Scheme?

The Quarterly Return Monthly Payment (QRMP) scheme is available to taxpayers with an annual aggregate turnover of up to ₹5 crore. Under QRMP:

• GSTR-1 is filed quarterly (instead of monthly)
• GSTR-3B is filed quarterly (but tax must be paid monthly via challan PMT-06)
• Reduces compliance burden from 24 returns per year to 8 returns per year

To opt into or out of QRMP, the window is open from the 1st of the second month of each quarter to the last day of the first month of the next quarter.

Frequently Asked Questions (FAQs)

Can I file GSTR-3B before GSTR-1?

Yes, technically, you can file GSTR-3B before GSTR-1. However, it is always recommended to file GSTR-1 first so that your outward supply data populates in your buyers’ GSTR-2B before you claim ITC in GSTR-3B. Filing in the wrong order can cause ITC mismatches.

If I have no sales in a month, do I still need to file GSTR-3B?

Yes. A nil GSTR-3B must be filed even if there are zero transactions. Non-filing attracts late fees of ₹20 per day (₹10 CGST + ₹10 SGST) even for nil returns.

How many times can GSTR-1 be amended?

Invoices in GSTR-1 can be amended through a subsequent GSTR-1 filing. However, amendments for a financial year can only be made up to the return for October of the following year or the date of filing the annual return (GSTR-9), whichever is earlier.

What is GSTR-2B, and how is it different from GSTR-2A?

GSTR-2B is a static, auto-generated statement of available ITC based on your suppliers’ GSTR-1 filings. It is fixed for a tax period and does not change. GSTR-2A is a dynamic statement that updates whenever a supplier files or amends their GSTR-1. For ITC claims, the GST portal uses GSTR-2B as the reference.

📞 Need expert help? BMC Associates — CA Firm in Delhi NCR — offers professional GST, tax, audit & compliance services. Call us at +91-991-084-9998