What is GSTR-3B?
GSTR-3B is the return in which you declare the month's (or quarter's) tax and pay it, net of the input tax credit (ITC) you claim on your purchases (section 39 of the CGST Act). GSTR-1 lists your sales; GSTR-3B settles the money.
For an online store it comes together from three places:
| Part of GSTR-3B | Comes from | Can you change it? |
|---|---|---|
| Table 3.1 and 3.2: tax on your sales | Your GSTR-1 (and GSTR-1A) | No, since the July 2025 period. Correct GSTR-1 instead |
| Table 4: input tax credit | GSTR-2B, built from your suppliers' GSTR-1 | Yes: you check it and record reversals |
| Table 5.1: interest and late fee | The portal's own calculation | Interest can be edited; late fee is fixed |
| Table 6.1: payment | Your credit and cash ledgers | You choose how credit is used, within the rules |
Table 3: tax on your sales
- 3.1(a) taxable sales at ordinary rates;
- 3.1(b) zero-rated sales: exports;
- 3.1(c) nil-rated and exempt sales;
- 3.1(d) purchases on which you pay tax yourself under reverse charge;
- 3.1(e) non-GST sales;
- 3.2 of the sales in 3.1(a), those made inter-state to unregistered buyers, by state.
The figures in 3.1 (except reverse charge) and 3.2 are filled from your GSTR-1 for the same period. Since the July 2025 period they cannot be edited in GSTR-3B (GSTN advisory of 7 June 2025). A mistake found after filing GSTR-1 is fixed once through GSTR-1A, before GSTR-3B is filed, or in a later month.
Table 4: input tax credit
Table 4 is filled from your GSTR-2B, the statement of the credit your suppliers' returns give you. GSTR-2B is ready on the 14th of the next month.
Since October 2024, invoices from suppliers first land in the Invoice Management System (IMS), where you can accept, reject or keep them pending. Anything you do not act on is treated as accepted when GSTR-2B is made. If you act after the 14th, you can have GSTR-2B worked out again, up to filing GSTR-3B.
What online sellers usually claim: stock bought from GST-registered suppliers, packaging, courier and logistics bills, payment gateway fees, marketplace commissions, software and advertising billed with GST.
What has to be reversed in Table 4(B): credit on things the law blocks (section 17(5)), such as food and drink for staff, free gifts and samples, and goods lost or written off.
How is tax paid?
Credit is used before cash, and in a set order (section 49 and Rule 88A of the CGST Rules):
- IGST credit pays IGST first;
- what is left of IGST credit pays CGST and SGST, in any order;
- CGST credit pays CGST, then IGST; SGST credit pays SGST, then IGST;
- CGST credit can never pay SGST, nor SGST credit CGST.
Whatever credit does not cover is paid in cash from your electronic cash ledger, topped up by challan (PMT-06) through net banking, UPI, card or NEFT.
Filing it, step by step
- File GSTR-1 by the 11th. GSTR-3B cannot be filed before it (section 39(10)).
- After the 14th, check IMS and GSTR-2B.
- Open GSTR-3B: Table 3 is already filled and locked; Table 4 is filled from GSTR-2B. Record any reversals.
- Save, then Proceed to payment. The portal shows tax, credit used and cash needed.
- Deposit the cash shortfall by challan if the cash ledger is short.
- Offset the liability, then file with EVC or DSC by the 20th (the 22nd or 24th for quarterly filers).
Where online sellers go wrong
- Claiming credit that is not in GSTR-2B. Since 2022, credit must appear in GSTR-2B to be claimed (section 16(2)(aa)). A supplier who has not filed GSTR-1 holds up your credit.
- Forgetting reverse charge. Some purchases, such as services from a goods transport agency that has not opted to charge tax, are taxed in your hands in 3.1(d), and the same tax comes back as credit in Table 4.
- Paying cash with credit lying unused. The portal's suggested offset follows Rule 88A, but check it before you pay: cash paid cannot be turned back into credit.
- Filing GSTR-1 late. It holds GSTR-3B back, and the late fees stack.