How to File GSTR-3B: a step-by-step guide

7 min read · GST

GSTR-3B is the monthly (or quarterly) summary return where you declare your outward supplies, claim input tax credit (ITC), and pay the net GST due. It is not an invoice-level return — it is a consolidated summary — but it is the return that actually settles your tax. Here is how to file it, step by step.

Due dates

For most monthly filers, GSTR-3B is due by the 20th of the following month. Businesses under the QRMP (Quarterly Return, Monthly Payment) scheme file quarterly, generally by the 22nd or 24th of the month after the quarter, depending on the state group your principal place of business falls in. As of Sep 2026 these are the standard dates, but the GSTN sometimes issues extensions — confirm the applicable date for your GSTIN on the portal before you rely on it.

Step 1 — Reconcile before you start

Before opening the return, match your books against GSTR-2B (your auto-drafted ITC statement) so you only claim credit that your suppliers have actually reported. Doing this first is what prevents notices later — ITC claimed but not reflected in 2B is the most-scrutinised figure in the return.

Step 2 — Table 3.1: outward supplies

Table 3.1 is where you declare the taxable value and tax on your outward (sales) supplies — split across taxable, zero-rated, nil-rated/exempt, and inward supplies liable to reverse charge. Under the rationalised structure in force since 22 September 2025, most supplies now sit at 5% or 18%, with a 40% de-merit rate on a narrow set of goods; the earlier 12% and 28% slabs were abolished for new supplies. Make sure the rate applied on your invoices matches the current slab for each item.

Step 3 — Table 4: input tax credit

Table 4 captures ITC — credit available, credit reversed (for example under Rule 42/43 or for non-payment within 180 days), and ineligible credit. Net eligible ITC from this table is what offsets your output liability. Over-claiming here, or forgetting a required reversal, is the single most common source of GSTR-3B error.

Step 4 — Pay and offset

The portal computes your net liability after setting off ITC. Any balance is paid in cash via challan into the electronic cash ledger, following the prescribed set-off order. You cannot submit the return until the liability is fully discharged.

Late fee and interest

Miss the deadline and two charges apply. The late fee accrues per day of delay (₹50/day for a return with liability, ₹20/day for a nil return, each capped) — split across CGST and SGST. Interest under §50 runs at 18% per annum on the tax paid in cash (i.e. the portion not covered by ITC), from the due date to the date of payment. These are indicative figures as of Sep 2026 — verify the current amounts against the latest CBIC notification or with your CA.

Common errors to avoid

Claiming ITC not appearing in GSTR-2B; forgetting reverse-charge liability in 3.1(d); mismatches between the values in GSTR-1 and GSTR-3B for the same period; and filing a nil return when you actually had exempt or zero-rated supplies to report. Each of these is a routine trigger for a system-generated notice.

General information, not tax advice. Due dates, fees and rates change — confirm the current figures against the latest CBIC notification or with your CA.