What is GSTR-3B?
GSTR-3B is a summary return filed every month (or quarterly under QRMP). It's where you:
- Report total taxable outward supplies and tax liability.
- Claim Input Tax Credit (ITC) from your purchases.
- Adjust ITC and pay the net tax in cash.
Unlike GSTR-1 which is invoice-level, GSTR-3B is just numbers — five values per tax head (CGST/SGST/IGST/Cess). But getting those numbers right needs careful reconciliation.
Before You File
- GSTR-1 for the same period is filed (or at least drafted).
- All purchase invoices for the period are entered.
- GSTR-2B for the period is downloaded and reconciled.
- Bank/electronic cash ledger has enough balance for net tax (or you're ready to pay).
Step 1 — Generate Draft GSTR-3B
- Go to GST → Returns → GSTR-3B.
- Select the period.
- Click "Generate Draft".
iAccounting auto-populates each table:
| Table | What It Contains | Source |
|---|---|---|
| 3.1(a) | Outward taxable supplies (other than zero-rated, nil-rated, exempt) | Sales register |
| 3.1(b) | Outward taxable supplies (zero-rated) | Exports invoices |
| 3.1(c) | Other outward supplies (nil-rated, exempt) | Nil/exempt sales |
| 3.1(d) | Inward supplies (liable to reverse charge) | RCM purchases |
| 3.1(e) | Non-GST outward supplies | Non-GST sales (e.g. petrol/diesel) |
| 3.2 | Inter-state supplies to unregistered, composition, UIN holders | From 3.1(a) |
| 4(A) | ITC available — all heads | Purchase register |
| 4(B) | ITC reversed (Rule 42/43 etc.) | Calculated |
| 4(C) | Net ITC | 4(A) − 4(B) |
| 4(D) | Ineligible ITC | Blocked credits |
| 5 | Exempt, nil & non-GST inward supplies | Auto from purchase |
| 6.1 | Payment of tax | Computed |
Step 2 — Reconcile ITC with GSTR-2B
This is the most critical step. The law says: ITC can only be claimed if the corresponding invoice appears in GSTR-2B (with limited exceptions).
In iAccounting:
- Go to GST → GSTR-2B Reconciliation.
- Download/sync GSTR-2B from the GST portal (one-click).
- System matches each purchase invoice against GSTR-2B.
Matches fall in 5 buckets:
| Status | Meaning | Action |
|---|---|---|
| ✓ Matched | Invoice in your books = invoice in 2B | Claim ITC |
| ⚠ Partial | Small mismatch in value/tax | Verify; usually accept |
| ✗ In Books, not in 2B | Vendor didn't file GSTR-1 yet | Follow up with vendor; claim later |
| ✗ In 2B, not in Books | You missed entering the invoice | Enter the missing invoice |
| ~ Mismatch | GSTIN or invoice number differs | Investigate which is correct |
Click "Apply Reconciliation" to update GSTR-3B's Table 4(A) with only the matched ITC.
Step 3 — Reverse Charge Mechanism (RCM)
If you've received supplies notified under RCM (e.g., legal services, goods transport from unregistered GTA, advocate fees), you must:
- Pay tax under RCM in cash (Table 3.1(d)).
- Claim it back as ITC in the same return (Table 4(A)(3)).
iAccounting handles both legs if you've marked the purchase voucher as "RCM applicable". Verify the RCM number matches between Tables 3.1(d) and 4(A)(3).
Step 4 — Compute & Pay Net Tax
The bottom of GSTR-3B shows:
Output tax liability − ITC available = Net tax payable in cash
This must be paid from your Electronic Cash Ledger. If insufficient, deposit via Challan PMT-06:
- Click "Create Cash Challan".
- System fills in CGST / SGST / IGST / Cess amounts.
- Click "Pay via GSTN Portal" → net banking / NEFT / RTGS.
- Once paid, the cash ledger updates within 24 hours.
Step 5 — Push GSTR-3B to Portal
- Click "Push GSTR-3B".
- iAccounting uploads all values to the GST portal.
- Log in to gst.gov.in → Returns → GSTR-3B → "Proceed to File".
- Verify the numbers match.
- Click "Offset Liability" — system applies ITC against tax.
- Pay any remaining cash tax via challan.
- File with DSC or EVC.
Step 6 — Auto-post Tax Entries to Books
After filing, iAccounting auto-creates these journal entries:
| Entry | Dr / Cr |
|---|---|
| Output CGST / SGST / IGST Payable | Dr |
| Input CGST / SGST / IGST Receivable | Cr |
| GST Payable (Net) | Cr (or Dr if refundable) |
| Cash/Bank (for net cash paid) | Cr |
Your books now reflect the GST liability correctly. The GST Payable ledger should be near-zero after the filing.
Due Dates
| Frequency | Due Date |
|---|---|
| Monthly | 20th of next month |
| QRMP (last month of qtr) | 22nd or 24th of month after qtr (state-wise) |
| QRMP (PMT-06 for months 1&2) | 25th of next month |
Late filing penalty
- ₹50/day (₹25 + ₹25), or ₹20/day for nil returns.
- Plus 18% interest on net tax payable.
Common GSTR-3B Issues
- Claiming ITC not in 2B — leads to notice and demand.
- Mismatch with GSTR-1 — system auto-compares; flagged in scrutiny.
- Forgetting RCM tax — interest applies; can't claim ITC unless paid.
- Wrong place-of-supply on outward supplies — IGST vs CGST+SGST confusion.
- Reversing ITC on bills not received in 180 days — Rule 37 reversal.
- Filing GSTR-3B before GSTR-1 — system allows it but creates mismatch issues.