GSTR-1 vs GSTR-3B: what each GST return reports and how they connect

Two returns carry most of a regular taxpayer's GST work each month. They look similar, but they do different jobs.

The one-line difference

GSTR-1 tells the department, and your customers' return, what you sold. GSTR-3B tells the department how much tax you owe after credit, and you pay it there.

Side by side

	GSTR-1	GSTR-3B
What it is	Statement of sales (outward supplies)	Summary return of tax liability and credit
Detail level	Invoice by invoice	Totals only
Tax paid with it	No	Yes
Due date (monthly filers)	11th of the next month	20th of the next month
Who uses the data	Your customers, as input tax credit	The department, to check liability
Can it be revised	Corrected through later amendments	Cannot be revised; correct in a later month

How the data flows

1. You file GSTR-1 with each sale to a registered buyer.
2. The buyer's GSTR-2B for that month shows your invoice as available credit.
3. The buyer claims that credit in their GSTR-3B, reducing the tax they pay.
4. You file your GSTR-3B, declare the tax on your sales, subtract the credit you are entitled to, and pay the rest.

If you file GSTR-1 late, your customers cannot claim credit for that month, and they may ask you to correct it. This is why GSTR-1 matters even though no tax is paid with it.

The tax payment sequence

In GSTR-3B, credit is applied in a set order: integrated tax credit first, against IGST, then CGST, then SGST; CGST credit against CGST then IGST; and SGST credit against SGST then IGST. CGST credit cannot be used for SGST and the reverse. Whatever remains is paid in cash from the cash ledger.

What triggers mismatch notices

• GSTR-1 shows more tax than GSTR-3B. The system reads this as under-reported liability.
• Credit claimed exceeds GSTR-2B. The portal flags excess claims.
• Invoices missing from GSTR-1. Your customer's credit is denied and they ask you why.
• Wrong period. Invoices reported in a different month from the one they belong to.

A monthly routine that keeps them aligned

1. Close sales for the month and list all invoices and credit notes.
2. File GSTR-1 by the 11th.
3. When GSTR-2B is generated, compare it against your purchase records and chase missing suppliers.
4. Prepare GSTR-3B by comparing it with GSTR-1 and GSTR-2B.
5. Pay and file by the 20th.

On the quarterly scheme (QRMP), GSTR-1 is filed quarterly by the 13th, and GSTR-3B quarterly by the 22nd or 24th, with tax paid monthly by challan by the 25th in the first two months. Dates are on the compliance calendar.

A step-by-step walk through both returns is in how to file GST returns yourself. Terms like ITC and GSTIN are in the glossary. For monthly filing handled for you, see GST services.