How to File GSTR-3B: Monthly Summary Return with ITC and Tax Payment Guide

What is GSTR-3B?

GSTR-3B is a monthly (or quarterly under QRMP) self-assessed summary return that every regular GST taxpayer must file. Unlike GSTR-1 which reports invoice-level detail, GSTR-3B is a consolidated summary where you declare:

• Total outward supplies (sales) and tax liability
• Total inward supplies eligible for Input Tax Credit (ITC)
• Net tax payable after adjusting ITC
• Tax actually paid through the electronic cash ledger

You must pay the full tax liability before filing GSTR-3B — the portal does not allow filing with outstanding dues.

Who Must File GSTR-3B?

All regular GST-registered taxpayers must file GSTR-3B, including:

• Monthly filers — file every month by the 20th
• QRMP quarterly filers — file every quarter by the 22nd or 24th (state-wise)
• e-Commerce operators (for their own supplies)

Not required for: Composition dealers (file CMP-08 instead), TDS deductors, OIDAR providers, Non-Resident Taxable Persons.

Due Dates for GSTR-3B

Category	Due Date
Monthly filers (all states)	20th of following month
QRMP — Category X states (15 states)	22nd of month after quarter
QRMP — Category Y states (21 states)	24th of month after quarter

Understanding GSTR-3B Structure

Section 3.1 — Details of Outward Supplies and Inward Supplies Liable to Reverse Charge

This is where you declare your total sales summary:

• 3.1(a) — Outward taxable supplies (other than zero-rated, nil-rated and exempted): Total taxable turnover for the period with corresponding IGST, CGST, SGST. Important: Exclude RCM liability from the tax columns here — only include taxable value.
• 3.1(b) — Outward taxable supplies (zero-rated): Exports and SEZ supplies. IGST paid on exports or nil if supplied under LUT/Bond.
• 3.1(c) — Other outward supplies (nil-rated, exempted): Exempt and nil-rated supplies like fresh vegetables, milk, etc.
• 3.1(d) — Inward supplies (liable to reverse charge): RCM liability you owe as a buyer — e.g., freight from unregistered GTA, advocate fees, import of services. This is always paid in cash (no ITC offset allowed at the time of payment).
• 3.1(e) — Non-GST outward supplies: Petroleum, liquor — supplies outside GST scope.

Section 3.2 — Inter-State Supplies

Break-up of inter-state supplies made to unregistered persons, composition dealers, and UIN holders — state-wise.

Section 4 — Eligible Input Tax Credit

The most critical section for ITC claim:

• 4A(1) — ITC from GSTR-2B (B2B): ITC on inward supplies from registered suppliers as per your GSTR-2B. This is auto-populated from GSTR-2B.
• 4A(2) — ITC on imports of goods: IGST paid on goods imported into India.
• 4A(3) — ITC on RCM (inward supplies): ITC on the RCM you paid under 3.1(d). Auto-populated from GSTR-2B RCM summary.
• 4A(5) — All other ITC: ITC on import of services, IGST on ocean freight, etc.
• 4B — ITC Reversed: ITC reversal for Rule 42/43, Rule 37 (non-payment to supplier), etc.
• 4D — Other ITC: ITC reclaimed after reversal (Rule 37A).

Section 5 — Values of Exempt, Nil-Rated and Non-GST Inward Supplies

For businesses with mixed supplies, report the exempt/nil-rated inward supplies — relevant for proportionate ITC reversal under Rule 42.

Section 6 — Payment of Tax

This section shows how tax liability is settled:

• Integrated Tax (IGST) payable → settled first using IGST ITC, then CGST/SGST ITC, then Cash
• Central Tax (CGST) payable → settled using CGST ITC, then Cash
• State Tax (SGST) payable → settled using SGST ITC, then Cash

Interest (18% p.a. on late payment) and late fee are always paid in cash — no ITC offset.

How ITC Flows from GSTR-2B to GSTR-3B

GSTR-2B is the auto-populated ITC statement generated on the 14th of every month. It shows:

1. All B2B invoices filed by your suppliers in their GSTR-1 where you are the recipient
2. ITC from ISD distributions (GSTR-6)
3. RCM ITC (which you paid in previous month's GSTR-3B)

When you open GSTR-3B, Section 4A values are auto-populated from your GSTR-2B. You can edit them downward (if you choose not to claim some ITC) but cannot claim more than what appears in GSTR-2B.

Step-by-Step GSTR-3B Filing

1. Pay tax first — create a GST challan (PMT-06 for QRMP, or regular challan for monthly) and deposit the net tax due via net banking or UPI. Cash enters your Electronic Cash Ledger.
2. Open GSTR-3B for the period on the GST portal.
3. Fill Section 3.1(a) — enter your total taxable turnover and auto-computed tax (or enter manually).
4. Fill 3.1(d) — enter RCM liability if applicable.
5. Fill Section 4A — verify auto-populated ITC from GSTR-2B. Add any import ITC.
6. Fill Section 4B — enter any ITC reversals.
7. Section 6 auto-computes net tax payable. Verify it matches your challan.
8. Click CONFIRM (this freezes the data — cannot edit after this).
9. File using DSC or EVC (OTP to registered mobile/email).
10. ARN is generated — filing is complete.

Late Fee and Interest

• Late fee: ₹25/day (₹12.50 CGST + ₹12.50 SGST), maximum ₹5,000 per return. For nil returns, ₹10/day max ₹500.
• Interest on late tax payment: 18% per annum calculated from the due date to the actual payment date.
• The portal auto-computes both when you file late. Use the RE-COMPUTE INTEREST button to refresh the calculation.

Practice GSTR-3B on IndIaTaxSim

IndIaTaxSim simulates the complete GSTR-3B workflow including GSTR-2B cross-GSTIN ITC pre-population, RCM handling, credit ledger offset, late fee/interest calculation, and the payment flow via challan before filing. The simulation accurately reflects the real portal's 4-head tax payment logic (IGST → CGST → SGST) and Electronic Cash/Credit Ledger mechanics.