How to file GSTR-3B: a step-by-step guide
Short answer
GSTR-3B is the monthly self-assessed summary return where you declare total outward supplies, the input tax credit (ITC) you claim and the net GST payable. To file it, log in to the GST portal, open the GSTR-3B tile for the period, verify the auto-filled values, offset your liability with ITC and cash, then submit with a DSC or EVC.
Updated 2026-06-03 · 399Apps · General GST information, not tax advice
How to file GSTR-3B on the GST portal: step by step
GSTR-3B is filed online at gst.gov.in. Much of it now auto-populates from your GSTR-1 and GSTR-2B, so most of the work is verification.
- 1
Log in and open GSTR-3B
Go to Services → Returns → Returns Dashboard, select the period, and click "Prepare Online" under the Monthly Return GSTR-3B tile.
- 2
Review the auto-populated values
Table 3.1 (outward supplies) is pre-filled from your GSTR-1 and Table 4 (ITC) from GSTR-2B. Cross-check both against your books before accepting.
- 3
Enter the remaining details
Add Table 3.2 (inter-state supplies to unregistered/composition persons), Table 3.1.1 (e-commerce supplies, where applicable) and any reverse-charge liability.
- 4
Confirm and claim eligible ITC
In Table 4, accept the eligible input tax credit from GSTR-2B and reverse blocked or ineligible credit (Section 17(5), personal use, etc.).
- 5
Check the liability and pay
The portal computes net tax payable after ITC. Create a challan (PMT-06) and pay any cash shortfall via net banking, UPI or NEFT/RTGS so the cash ledger covers the liability.
- 6
Offset and file
Click "Make Payment / Set-off" to use ITC and cash against the liability, then file the return with a DSC (companies/LLPs) or EVC (OTP).
What is GSTR-3B?
GSTR-3B is a self-declared summary return that every regular GST taxpayer files for each tax period. Unlike GSTR-1 (which is invoice-level), GSTR-3B reports consolidated figures: total outward supplies, inward supplies liable to reverse charge, the input tax credit claimed, and the net GST paid in cash. It is the return through which tax is actually paid.
GSTR-3B cannot be revised once filed, so the summary you submit — and the ITC you claim — is final for that period and is reconciled against your GSTR-1 and GSTR-2B.
GSTR-3B due dates (monthly and QRMP)
Your due date depends on whether you file monthly or under the QRMP scheme:
- • Monthly filers: due by the 20th of the following month.
- • QRMP (quarterly) filers: due by the 22nd or 24th of the month after the quarter, staggered by your principal state of registration.
- • QRMP taxpayers still pay tax monthly for the first two months of a quarter via challan PMT-06 (the 35% / self-assessment method).
GSTR-3B vs GSTR-1: how they connect
GSTR-1 reports the invoice-level detail of your sales; GSTR-3B is the summary on which you pay tax. The GST system now links them: your outward-supply liability in GSTR-3B Table 3.1 auto-populates from GSTR-1, and your ITC in Table 4 auto-populates from GSTR-2B. Filing an accurate GSTR-1 first therefore makes GSTR-3B faster and reduces mismatch notices.
Auto-population and locking of values
To curb errors and fake-ITC claims, the portal increasingly pre-fills and hard-locks GSTR-3B fields from GSTR-1/IFF and GSTR-2B. You can still report genuine adjustments where allowed, but large unexplained deviations from the auto-filled liability or ITC can trigger system flags — so reconcile your books to GSTR-2B before filing.
Common GSTR-3B mistakes to avoid
Watch for: claiming ITC not reflected in GSTR-2B, forgetting to reverse blocked or ineligible credit, missing reverse-charge liability, mismatches between GSTR-1 and GSTR-3B outward supplies, and late filing — which attracts 18% interest on tax paid late plus a per-day late fee.
How 399Apps helps
Nidhi Books (by 399Apps) keeps your books GSTR-3B-ready: it tracks output tax on every invoice and eligible ITC on purchases, and exports a GSTR-3B summary that matches your GSTR-1 — so you reconcile and file with confidence instead of re-keying totals.
How to file GSTR-3B — frequently asked questions
What is the due date for GSTR-3B? +
Can GSTR-3B be revised after filing? +
How is ITC claimed in GSTR-3B? +
Is GSTR-3B mandatory for a nil return? +
What is the difference between GSTR-3B and GSTR-1? +
GST billing, returns & e-invoicing — done automatically
Nidhi Books raises GST-compliant invoices and prepares GSTR-1 and GSTR-3B exports, with unlimited users from ₹399/month for your first app (+₹99/month per add-on, prices exclude GST). Free for 14 days.