GSTR-1 vs GSTR-3B: Differences, Due Dates and How They Link

GSTR-1 and GSTR-3B are the two returns almost every regular GST-registered business files. GSTR-1 is your sales report: it lists your outward supplies invoice by invoice. GSTR-3B is your tax payment return: a summary where you declare total tax, claim input tax credit and pay the balance in cash.

You need to file both. Since the July 2025 tax period, the two are tightly linked: what you report in GSTR-1 becomes the locked sales liability in your GSTR-3B.

What is the difference between GSTR-1 and GSTR-3B?

Think of GSTR-1 as the detail and GSTR-3B as the bill. Your customers’ input tax credit depends on GSTR-1; your own tax payment happens through GSTR-3B.

	GSTR-1	GSTR-3B
What it reports	Outward supplies (sales), invoice-wise for B2B; summary for most B2C	Summary of sales, purchases under reverse charge, ITC claimed and tax payable
Tax payment	No payment with this return	Tax, interest and late fee are paid while filing
Who uses the data	Your buyers: it flows to their GSTR-2B	You: it settles your tax liability
Monthly due date	11th of the next month	20th of the next month
QRMP (quarterly) due date	13th of the month after the quarter (IFF optional for months 1 and 2)	22nd or 24th of the month after the quarter, depending on your state
Can it be revised?	Corrected through GSTR-1A (once per period) or amendments in later GSTR-1	Cannot be revised once filed

Input tax credit (ITC) means the GST you paid on purchases that you can deduct from the GST you collect on sales.

Who has to file GSTR-1 and GSTR-3B?

Every normal taxpayer registered under GST files both, even in a month with no business (a nil return). Some registrations follow different returns:

• Composition taxpayers pay tax through CMP-08 every quarter and file GSTR-4 once a year. See our composition scheme guide.
• Non-resident taxpayers, input service distributors and TDS/TCS deductors file their own specific returns.
• Small businesses with turnover up to ₹5 crore can choose quarterly filing under the QRMP scheme, but still pay tax monthly.

What are the due dates for GSTR-1 and GSTR-3B?

Monthly filers

• GSTR-1: 11th of the following month. Example: April sales are due by 11 May.
• GSTR-3B: 20th of the following month. Example: April’s GSTR-3B is due by 20 May.

Quarterly filers under QRMP

• GSTR-1: 13th of the month after the quarter. Invoices for the first two months can optionally go through the Invoice Furnishing Facility (IFF) between the 1st and 13th of the next month.
• GSTR-3B: 22nd of the month after the quarter for states such as Maharashtra, Gujarat, Karnataka, Tamil Nadu, Kerala, Telangana, Andhra Pradesh, Madhya Pradesh, Chhattisgarh and Goa (plus some UTs). 24th for the remaining states and UTs, including Rajasthan, Delhi, Uttar Pradesh, Punjab, Haryana, West Bengal and Bihar.

Tip: The government sometimes extends due dates by notification, usually for specific states or after portal outages. Always check the GST portal’s return dashboard for the period you are filing.

How are GSTR-1 and GSTR-3B linked?

The link has become much tighter over the last two years. Three rules matter.

1. GSTR-1 auto-fills GSTR-3B, and the liability is locked

The portal pre-fills Table 3.1 of GSTR-3B (your outward tax liability) from GSTR-1, GSTR-1A and IFF. From the July 2025 tax period, this auto-filled liability is non-editable. The inter-state supplies table (3.2) is also auto-filled and locked from the same period.

So if your GSTR-1 has a mistake, you can no longer “fix it quietly” in GSTR-3B.

2. GSTR-1A is your correction window

GSTR-1A lets you add missed invoices or correct ones you reported in GSTR-1 for the same tax period. You file it after GSTR-1 and before GSTR-3B. It can be filed only once per period.

Watch out: If you have already filed GSTR-3B, a GSTR-1A correction will not change that month’s GSTR-3B. You would then correct it through amendments in a later period’s returns, and pay any interest due.

3. GSTR-1 must come first

You cannot file GSTR-3B for a period until GSTR-1 for that period is filed. Similarly, the portal can block you from filing GSTR-1 if earlier GSTR-3B returns are pending. Missing one return quickly holds up the next.

Why your GSTR-1 matters to your customers

When you file GSTR-1 (or IFF), your B2B invoices flow into your buyers’ GSTR-2B. That is the statement they use to claim ITC. Since October 2024, buyers also act on these invoices through the Invoice Management System (IMS): accepting, rejecting or keeping them pending.

If you file GSTR-1 late, or with a wrong GSTIN, your buyer’s credit is delayed. Our guide on ITC not showing in GSTR-2B explains the buyer’s side.

What happens if you file late?

• Late fee applies to both returns, with caps based on turnover.
• Interest at 18% a year applies to tax paid late through GSTR-3B, on the portion paid in cash. From the January 2026 tax period, the portal auto-calculates this interest in the next GSTR-3B, and you cannot reduce the auto-filled figure.
• Three-year time bar: a return cannot be filed once three years have passed from its due date. The portal began enforcing this from the November 2025 tax period.

See the full breakdown in our guide to GST late fees and interest.

Example: A trader files April’s GSTR-1 on 11 May. On 15 May she notices one invoice of ₹50,000 + ₹9,000 GST (₹4,500 CGST + ₹4,500 SGST) was missed. She adds it in GSTR-1A before filing GSTR-3B on 20 May. GSTR-3B then picks up the extra ₹9,000 liability automatically.

How to file GSTR-1 and GSTR-3B each month

1. Close your sales register and match it with invoices issued (and e-invoices, if applicable).
2. Upload B2B invoices, B2C summary, credit/debit notes and HSN summary in GSTR-1. File it with DSC or EVC by the 11th.
3. Review your auto-filled GSTR-3B. If sales are wrong, file GSTR-1A first.
4. Check GSTR-2B and IMS for purchase invoices, and decide which ITC you can claim.
5. Pay any cash balance and file GSTR-3B by the 20th.

Common mistakes

• Treating GSTR-3B as the “real” return and filing GSTR-1 casually. Since July 2025, GSTR-1 decides your GSTR-3B liability.
• Filing GSTR-3B before checking GSTR-1A. Once GSTR-3B is filed, that period’s correction window has passed.
• Claiming ITC that is not in GSTR-2B. This is a common trigger for notices.
• Wrong buyer GSTIN or wrong place of supply in GSTR-1, which charges IGST instead of CGST + SGST (or vice versa) and denies your buyer credit.
• Skipping nil returns. Late fees still apply when you had no sales. Use nil filing by SMS to stay compliant in seconds.

What to do next

• Set calendar reminders for the 11th and 20th (or 13th and 22nd/24th if you are on QRMP).
• Reconcile your sales register with GSTR-1 every month before filing GSTR-3B.
• If returns are pending or your figures don’t match, our team can handle it through our GST return filing service.