How to File GSTR-3B Online: Step-by-Step

GSTR-3B is the return that matters most in practice. GSTR-1 tells the system what you sold. GSTR-3B is where you declare the tax on it, claim your input tax credit, set the two off against each other and pay the balance in cash. Interest, late fee and most scrutiny notices are all computed off what you put in this one form.

It is also a return you cannot revise. Once it is filed, it stays filed, and any mistake has to be carried forward and corrected in a later month. That is why the real work happens before you log in, not on the filing screen.

Who files GSTR-3B, and when

Every normal taxpayer registered under GST files GSTR-3B for every tax period, including periods with no business at all. Composition taxpayers, input service distributors, non-resident taxable persons and TDS/TCS deductors file their own returns instead.

The QRMP scheme (quarterly return, monthly payment) is open to taxpayers with aggregate turnover up to ₹5 crore in the previous financial year. If you are in it, you still pay tax monthly, either a fixed sum computed by the portal or the actual liability you work out yourself. Only the return is quarterly.

Dates are occasionally extended by notification, sometimes only for particular states or districts. Check the portal before relying on an extension you have heard about.

Before you log in: the reconciliation

Filing GSTR-3B takes fifteen minutes. Filing it correctly takes the hour before that. Four things should be settled first.

1. GSTR-1 (or IFF) is filed and correct

Your outward liability in GSTR-3B is pulled from GSTR-1, GSTR-1A and the IFF. The GSTR-1 due date is the 11th for monthly filers and the 13th of the month after the quarter for QRMP filers. Rule 59(6) also works the other way round: you cannot file GSTR-1 for a period if GSTR-3B for the previous period is still pending.

Before you file GSTR-1, match it against your sales register invoice by invoice. Check the place of supply (it decides IGST or CGST plus SGST), the recipient's GSTIN, credit notes, and advances received. A mistake here now flows straight into a GSTR-3B figure you cannot overwrite.

2. GSTR-2B and the Invoice Management System

Your input tax credit is limited, in practice, to what appears in GSTR-2B, the static statement of supplier-reported invoices generated for each period around the 14th. Since October 2024, the Invoice Management System (IMS) sits in front of it: you can accept, reject or keep pending each invoice your suppliers upload, and GSTR-2B is computed from those actions. If you change IMS actions after 2B is generated, you can have 2B recomputed before filing 3B.

Reconcile 2B against your purchase register:

• invoices in your books but missing from 2B: chase the supplier, and do not claim the credit yet;
• invoices in 2B but not in your books: find out whether they are genuine before accepting them in IMS;
• blocked credits under Section 17(5) (motor vehicles, food and beverages, works contracts for immovable property and so on): these appear in 2B but must not be claimed.

The four conditions that decide whether credit is yours at all are set out in our post on Section 16 and input tax credit.

3. Reverse charge and imports

Liability on inward supplies under reverse charge (legal fees from an advocate, goods transport agency services, specified imports of services) is paid in cash in Table 3.1(d) and then claimed back as credit in Table 4. It is the most commonly missed line in small-business returns.

4. Late items from previous periods

If an invoice from an earlier month is being reported now, tax on it is late and interest applies. From the February 2026 tax period the portal also populates a "Tax Liability Breakup, As Applicable" tab from the document dates of such supplies, and you must open it, check it and save it before filing.

Filing GSTR-3B on the portal, step by step

1. Log in at the GST portal and go to Services → Returns → Returns Dashboard. Select the financial year, quarter and period, then click Search.
2. On the GSTR-3B tile, choose Prepare Online. Answer the short questionnaire (for example, whether you have reverse charge supplies or interest to declare); it decides which tables open.
3. Table 3.1: outward supplies. This shows taxable supplies, zero-rated supplies, nil-rated and exempt supplies, inward supplies liable to reverse charge, and non-GST supplies. Values from GSTR-1/1A/IFF are auto-populated. For the July 2025 tax period onwards, the auto-populated liability is non-editable. Only items GSTR-1 does not capture, such as reverse charge inward supplies in 3.1(d), are entered by you.
4. Table 3.1.1: supplies through e-commerce operators under Section 9(5), where the operator pays the tax (restaurant services, certain passenger transport and accommodation). Auto-populated where applicable.
5. Table 3.2: inter-state supplies to unregistered persons, composition taxpayers and UIN holders, state by state. From the November 2025 tax period these values are also auto-populated and non-editable.
6. Table 4: eligible ITC. Auto-populated from GSTR-2B: imports, reverse charge credit, ISD credit and all other ITC, with reversals in 4(B) and ineligible credit in 4(D). These figures remain editable, but compare carefully. A 3B claim higher than your 2B is the commonest trigger for a scrutiny notice.
7. Table 5: exempt, nil-rated and non-GST inward supplies, split between inter-state and intra-state.
8. Table 5.1: interest and late fee. The portal computes interest on the system-determined delay. Review it rather than accepting it blindly. GSTN itself has issued advisories correcting wrongly auto-computed interest.
9. Click Save GSTR-3B. The portal validates the entries and flags warnings, for example where ITC claimed departs from 2B.
10. Proceed to Payment. The portal shows the tax payable, credit available and cash balance by head (IGST, CGST, SGST, cess). Use the system-suggested offset or change it within the legal order: IGST credit is used first, and CGST and SGST credit never cross over to each other.
11. If cash is short, Create Challan (PMT-06) and pay by net banking, UPI, card, or NEFT/RTGS. Once the payment reflects in the cash ledger, return to the return.
12. Click Make Payment / Post Credit to Ledger, confirm the liability breakup tab where it is shown, and then File GSTR-3B with DSC (mandatory for companies and LLPs) or EVC (OTP to the authorised signatory's mobile).
13. Download the filed return and the ARN acknowledgement and keep them with the month's working papers.

Correcting outward figures through GSTR-1A

Hard-locking changed how errors are fixed. If GSTR-1 overstated or understated a supply, or put it under the wrong state or rate, the route is:

1. Open GSTR-1A for the same tax period.
2. Add a missed invoice, or amend the invoice already reported in GSTR-1.
3. File GSTR-1A. The auto-populated GSTR-3B figures change accordingly.
4. File GSTR-3B.

GSTR-1A can be filed only once per tax period, and only until GSTR-3B for that period is filed. Check everything before you submit it. If you miss the window, the correction goes into GSTR-1 or IFF of a later period, and the tax effect follows in that period's 3B.

Filing a nil GSTR-3B

If you had no outward supplies, no reverse charge liability and no ITC for the period, you can file a nil return online with a single declaration, or by SMS to 14409 in the format NIL 3B <GSTIN> <MMYYYY> from the registered mobile of the authorised signatory, followed by the confirmation code sent back to you.

File nil returns on time. A nil return filed late still attracts a late fee, and continuous non-filing is the leading cause of GSTIN cancellation, nil periods included.

Monthly calendar at a glance

If you also deduct TDS, the same month-end close feeds your quarterly TDS returns; see how to file a TDS return.

What if it goes wrong?

You filed with a mistake. There is no revision. Add an omitted liability in the next month's return and pay interest at 18% a year from the original due date on the tax paid late. Overstated liability is adjusted by reducing a later month's figures through GSTR-1/IFF amendments. Missed credit can be claimed in a later month, but only up to 30 November following the end of the financial year, or the annual return date if earlier. After that, Section 16(4) bars it entirely.

You claimed more ITC than GSTR-2B shows. Reverse the excess in a later month's Table 4(B) with interest if it was used. Where the difference crosses the system threshold, the portal issues an intimation in DRC-01C. The equivalent for outward supplies, where GSTR-1 liability exceeds what 3B paid, is DRC-01B. Respond to either one, by paying the difference or explaining it, before your next GSTR-1 is due. An unanswered intimation can block that filing.

You missed the due date. File as soon as possible. Late fee runs per day and interest on cash tax per day; both are covered in detail in our post on what happens if a GST return is not filed on time.

A scrutiny notice arrives. A 3B-versus-2B or 3B-versus-GSTR-1 difference usually produces ASMT-10. It is a question, not a demand, and it is answered with a reconciliation. See what to do if you get a GST notice.

You did not file for months. E-way bill generation is blocked after two missed periods, GSTR-1 cannot be filed, and cancellation proceedings follow. The returns must be filed, oldest first, before anything else can be fixed. Returns more than three years past their due date are now barred on the portal and cannot be filed at all.

Your invoices are e-invoices. Liability for those flows from the IRN data into GSTR-1. An invoice not reported on the IRP will not appear, and the fix is on the e-invoice side first; see e-invoicing under GST.

If you would rather the reconciliation, GSTR-1, IMS actions and 3B were handled as one monthly routine, our GST return filing service does exactly that.