GSTR-3B Filing Guide: Declare, Offset and Pay Your GST

GSTR-3B is the return that actually moves money. It summarises your sales, takes credit for the GST you paid on purchases, and settles the difference with the government. Since 2025 much of it is pre-filled and partly locked, so the work has shifted from typing numbers to checking the sources those numbers come from.

This guide explains due dates, each table, the payment process, the locked-value rules and a full worked example.

Who files GSTR-3B and when is it due?

Every regular taxpayer files GSTR-3B for every period, including nil periods. Composition taxpayers, Input Service Distributors, non-resident taxpayers and TDS/TCS deductors file other returns instead.

Filer type	Due date
Monthly filer	20th of the following month
Quarterly (QRMP), Category X states/UTs	22nd of the month after the quarter
Quarterly (QRMP), Category Y states/UTs	24th of the month after the quarter

Which quarterly date applies depends on the state or union territory where you are registered, as notified by the government. QRMP filers also pay tax monthly for the first two months of each quarter through PMT-06 — see QRMP scheme and IFF.

Returns must be filed in sequence: you cannot file a GSTR-3B for October if September is still pending. And since the portal began enforcing the three-year limit from 2025, a GSTR-3B more than three years past its due date can no longer be filed.

What do the GSTR-3B tables mean?

Table	What it contains	Where the data comes from
3.1(a)	Outward taxable supplies (other than zero-rated, nil, exempt)	GSTR-1 / GSTR-1A / IFF
3.1(b)	Zero-rated supplies (exports, SEZ)	GSTR-1
3.1(c)	Nil-rated and exempt supplies	GSTR-1
3.1(d)	Inward supplies liable to reverse charge	GSTR-2B (partly) plus your own records
3.1(e)	Non-GST outward supplies	GSTR-1
3.1.1	Supplies through e-commerce operators	GSTR-1 / operator data
3.2	Inter-state supplies to unregistered persons, composition dealers and UIN holders	GSTR-1
4	Eligible ITC, reversals and ineligible ITC	GSTR-2B
5	Exempt, nil and non-GST inward supplies	Your purchase records
5.1	Interest and late fee	System-computed and your entries
6.1	Payment of tax	Ledger set-off

Which values are locked?

Following the GSTN advisory, from the July 2025 tax period the outward-supply liability auto-populated in GSTR-3B from GSTR-1, GSTR-1A or IFF cannot be edited in GSTR-3B. If the auto-filled liability is wrong, correct it through GSTR-1A before filing GSTR-3B. GSTR-1A can be filed only once per tax period, so check carefully before you submit it.

The ITC side works through GSTR-2B and the Invoice Management System (IMS). Supplier invoices you accept in IMS (or leave without action, which counts as deemed accepted) go into GSTR-2B's ITC-available section and flow into Table 4. Rejected invoices do not flow into GSTR-3B, and pending ones wait for a later period. You can change IMS actions and recompute GSTR-2B until GSTR-3B for that period is filed. How you reconcile all this is covered in GSTR-2B reconciliation.

How do I file GSTR-3B step by step?

1. File GSTR-1 (or IFF/GSTR-1A as applicable) first so liability flows in.
2. Review IMS: accept, reject or keep pending supplier records, then recompute GSTR-2B if you changed anything.
3. Log in to gst.gov.in and open Services > Returns > Returns Dashboard; choose the year and period.
4. On the GSTR-3B tile, click Prepare Online. Answer the questionnaire if shown.
5. Open Table 3.1 and check the auto-filled liability against your sales register. Fix differences through GSTR-1A, not here.
6. Enter reverse-charge purchases in 3.1(d) if they are not fully captured.
7. Open Table 4. Review eligible ITC and enter reversals (for example blocked credit or Rule 42/43 reversals) in 4(B).
8. Fill Table 5 for exempt and non-GST purchases, and check interest in 5.1.
9. Click Save GSTR-3B, then Proceed to Payment. The system shows the tax payable, ITC available and cash required.
10. If the cash ledger is short, click Create Challan, pay by net banking, UPI, card, NEFT/RTGS or over the counter, and return to the return.
11. Click Make Payment/Post Credit to Ledger to offset liability.
12. Tick the declaration and file with DSC or EVC. Download the filed return for your records.

How does ITC set-off work in GSTR-3B?

Credit is used in a fixed order:

• IGST credit is used first, against IGST liability, then against CGST and SGST in any order and proportion.
• CGST credit can be used against CGST and IGST, never SGST.
• SGST credit can be used against SGST and IGST, never CGST.
• IGST credit must be fully used before CGST or SGST credit is used.

The portal suggests a set-off, which you can adjust within these rules. Reverse-charge tax, interest and late fee always come from the cash ledger.

Worked example: a Nagpur printing press

A Nagpur printing press (Maharashtra, monthly filer) has these figures for September 2026:

Outward supplies (from GSTR-1):

• Intra-state B2B and B2C sales: taxable ₹6,00,000 at 18% → CGST ₹54,000, SGST ₹54,000
• Inter-state B2B sales: taxable ₹2,00,000 at 18% → IGST ₹36,000

Eligible ITC (from GSTR-2B):

• IGST ₹40,000 (paper bought from Gujarat)
• CGST ₹20,000, SGST ₹20,000 (local ink and repairs)

Reverse charge: legal fees ₹50,000 at 18% → CGST ₹4,500, SGST ₹4,500 payable in cash (and then claimable as ITC in the same return, if eligible).

Set-off of forward-charge liability:

Step	IGST	CGST	SGST
Liability	₹36,000	₹54,000	₹54,000
IGST credit ₹40,000 used: against IGST	−₹36,000
Balance IGST credit ₹4,000 used against CGST		−₹4,000
CGST credit ₹20,000		−₹20,000
SGST credit ₹20,000			−₹20,000
Cash payable	₹0	₹30,000	₹34,000

Now add reverse charge. The ₹9,000 RCM tax must be paid in cash. But the same ₹9,000 is also eligible ITC, claimed in Table 4(A)(3), so it adds CGST ₹4,500 and SGST ₹4,500 to the credit available against forward-charge liability. That cuts forward-charge cash to CGST ₹25,500 and SGST ₹29,500.

Total cash needed: ₹25,500 + ₹29,500 + ₹9,000 (RCM) = ₹64,000. The portal's payment screen works this out for you once Table 4 includes the RCM credit.

What does late filing cost?

Two separate charges apply:

• Interest under Section 50 on tax paid late, at the notified rate of 18% per annum. Since 2021, interest on tax declared in a late return is charged on the portion paid through the cash ledger, not on the portion covered by ITC (unless proceedings have started).
• Late fee under Section 47 for every day the return is late, at reduced amounts the government has notified, with a lower cap for nil returns.

Details and a calculation example are in GST late fee and interest.

What should you check before clicking file?

Because GSTR-3B cannot be revised, a short pre-filing checklist saves far more time than it costs. Run through these points every month:

1. Sales total. Does Table 3.1(a) plus 3.1(b), (c) and (e) equal the taxable, zero-rated, exempt and non-GST sales in your books for the period, after credit notes?
2. Tax head split. Is IGST shown only for inter-state supplies and exports, and CGST+SGST only for intra-state supplies? A wrong split cannot be fixed by moving amounts between heads later.
3. Reverse charge. Have you listed every RCM purchase — legal fees, goods transport agency, rent from unregistered persons where applicable, imports of services?
4. ITC source. Does Table 4(A) match your recomputed GSTR-2B, and have you resolved IMS pending items you meant to accept?
5. Reversals. Have you entered blocked credit, personal-use portions and common-credit reversals in Table 4(B)?
6. Cash ledger. Is there enough balance for RCM tax, interest and late fee, which cannot be paid with credit?
7. Previous period carry-overs. Are there invoices from an earlier month that your supplier reported late and which now appear in this GSTR-2B?

Nil GSTR-3B

If you had no sales, no purchases with ITC, no reverse-charge liability and nothing else to report, you still file a nil GSTR-3B. The portal offers a simplified online nil filing, and also nil filing by SMS from the authorised signatory's registered mobile number, provided there is no outstanding interest or late fee. A nil return filed late still carries a (lower) late fee, so do not let quiet months slip.

How do you correct a mistake after filing GSTR-3B?

A filed GSTR-3B cannot be revised. Corrections go into a later return:

1. Under-reported sales: add the missed value in the next month's Table 3.1 and pay the tax with interest under Section 50 from the original due date.
2. Over-reported sales: reduce the liability in a later month, where the portal permits, keeping a working note that links the adjustment to the original period.
3. ITC missed: claim it in a later GSTR-3B, as long as you are within the Section 16(4) time limit.
4. ITC claimed in excess: reverse it in Table 4(B), with interest if it was used.

Common mistakes in GSTR-3B

• Filing before GSTR-1. Liability will not populate, and you may under-declare.
• Trying to fix liability in 3B. Locked values cannot be edited; use GSTR-1A.
• Claiming ITC not in GSTR-2B. Credit beyond GSTR-2B is not allowed and invites notices.
• Forgetting reversals. Blocked credits, personal-use items and exempt-supply portions must be reversed in Table 4(B). See blocked input tax credit.
• Missing reverse charge. Legal fees, goods transport agency services and other RCM items must be paid in cash.
• Leaving IMS actions undone near the deadline. Rejected or pending choices change GSTR-2B; recompute before filing.
• Assuming the challan is the return. Paying the challan does not file GSTR-3B; you must still offset and submit.

Key takeaways

• GSTR-3B is due on the 20th (monthly) or the 22nd/24th after the quarter (QRMP).
• Outward liability auto-fills from GSTR-1/1A/IFF and has been non-editable since the July 2025 period.
• ITC comes from GSTR-2B, shaped by your IMS actions.
• Credit is set off in a fixed IGST-first order; RCM, interest and fees are cash only.
• GSTR-3B cannot be revised, so reconcile before you file.
• Returns more than three years overdue are barred.

Billing Software by Betterwork keeps sales, credit notes and purchase entries together, which makes it easier to compare the auto-filled values with your own books before you click file. For the difference between the two main returns, see GSTR-1 vs GSTR-3B.

This guide is general information, not tax advice. Rules last checked on 20 October 2026; confirm with your tax professional for your situation.