GSTR-1 vs GSTR-3B: Differences, Due Dates and How to Reconcile Them
Every regular GST taxpayer files two core returns: GSTR-1 and GSTR-3B. They are filed for the same period, both report your sales, and yet they serve different purposes. When the figures in the two don't match, the GST portal now flags it automatically, and you may receive a notice asking you to pay the difference or explain it.
This guide explains what each return does, their due dates, the 2025 changes that made reconciliation non-negotiable, and a practical monthly reconciliation routine.
Quick answer:GSTR-1 is a statement of outward supplies, reporting invoice-level details of your sales so your buyers can claim input tax credit. GSTR-3B is a summary return in which you declare total sales, claim ITC and pay your tax. GSTR-1 is due on the 11th of the next month (13th quarterly under QRMP), and GSTR-3B on the 20th (22nd or 24th for quarterly filers). The tax liability in GSTR-3B must match what you reported in GSTR-1.
Difference Between GSTR-1 and GSTR-3B
| Basis | GSTR-1 | GSTR-3B |
| Nature | Statement of outward supplies | Summary return with tax payment |
| Level of detail | Invoice-wise for B2B; summary for B2C | Consolidated totals only |
| Purpose | Passes data to buyers' GSTR-2B for ITC | Declares liability, claims ITC, pays tax |
| ITC claim | No | Yes |
| Tax payment | No | Yes, through cash and credit ledgers |
| Due date (monthly) | 11th of next month | 20th of next month |
| Due date (QRMP) | 13th of month after quarter (optional IFF monthly by 13th) | 22nd or 24th of month after quarter |
| Amendment | Through GSTR-1A before filing 3B, or in later GSTR-1 | No revision; corrections go in later returns |
The simplest way to remember it: GSTR-1 tells the system what you sold; GSTR-3B is how much tax you pay on it.
GSTR-1 Due Date
| Taxpayer type | Return | Due date |
| Monthly filer (turnover above ₹5 crore, or opted monthly) | GSTR-1 | 11th of the following month |
| Quarterly filer under QRMP | GSTR-1 | 13th of the month after the quarter |
| QRMP filer wanting to pass B2B data monthly | IFF (Invoice Furnishing Facility) | 13th of the following month (for first two months of the quarter) |
GSTR-3B Due Date
| Taxpayer type | Due date |
| Monthly filer | 20th of the following month |
| QRMP filer — Category X states (e.g. Gujarat, Maharashtra, Karnataka, Tamil Nadu, Kerala) | 22nd of the month after the quarter |
| QRMP filer — Category Y states (e.g. Delhi, Uttar Pradesh, Bihar, Rajasthan, Punjab, Haryana) | 24th of the month after the quarter |
QRMP filers pay tax monthly for the first two months of a quarter using PMT-06 by the 25th.
Late Fee for GSTR-1 and GSTR-3B
| Return | Late fee | Interest |
| GSTR-1 | ₹50 per day (₹25 CGST + ₹25 SGST); ₹20 per day for nil returns | Not applicable |
| GSTR-3B | ₹50 per day; ₹20 per day for nil returns | 18% per annum on tax paid late (on net cash liability) |
Maximum late fee caps are linked to turnover under CBIC notifications. Even with caps, repeated delays block e-way bill generation and can lead to registration suspension.
The three-year time bar
From July 2025, you cannot file GSTR-1, GSTR-3B and certain other returns after three years from their original due date. Old pending returns become permanently barred, so clear any backlog now.
GSTR-1 and GSTR-3B Mismatch: Why It Happens
Common causes:
- Invoices reported in GSTR-1 but missed in GSTR-3B (or the reverse).
- Credit notes reported in one return but not the other.
- Advances received taxed in 3B but adjusted differently in GSTR-1.
- Wrong place of supply, showing IGST in one return and CGST/SGST in the other.
- Amendments made in GSTR-1 without matching adjustments in 3B.
The 2025 change: liability is now locked
The outward liability in Table 3 of GSTR-3B is auto-populated from GSTR-1/IFF/GSTR-1A, and from July 2025 these auto-filled values can no longer be edited in GSTR-3B. If something is wrong, you must correct it through GSTR-1A before filing GSTR-3B for that period. This makes GSTR-1 accuracy critical.
GST Reconciliation: A Monthly Routine
1. GSTR-1 vs books of accounts
Before filing GSTR-1, match your sales register (Tally, Zoho, Busy or ERP) with the GSTR-1 draft:
- Total taxable value by rate.
- B2B invoices by GSTIN.
- Credit and debit notes.
- Exports and SEZ supplies.
2. GSTR-1 vs GSTR-3B
After GSTR-1 is filed, check that the auto-filled liability in GSTR-3B equals your books. Use GSTR-1A to fix errors before 3B.
3. GSTR-2B vs purchase register (ITC reconciliation)
Download GSTR-2B (generated on the 14th) and match it with your purchase register:
- Invoices in books but not in 2B: follow up with the supplier to file their GSTR-1.
- Invoices in 2B but not in books: verify whether they are genuine or wrongly uploaded.
- Use the Invoice Management System (IMS) to accept, reject or keep invoices pending before 2B is generated.
Claim ITC in GSTR-3B only to the extent supported by GSTR-2B, subject to Section 16 conditions.
4. Annual reconciliation
At year-end, reconcile GSTR-1, GSTR-3B, GSTR-2B and books before filing GSTR-9 annual return and, if applicable, GSTR-9C.
DRC-01B and DRC-01C Notices
| Form | Trigger | What you must do |
| DRC-01B | Liability in GSTR-1 exceeds GSTR-3B beyond a set threshold | Pay the difference through DRC-03 or explain in Part B within 7 days |
| DRC-01C | ITC claimed in GSTR-3B exceeds ITC in GSTR-2B beyond a set threshold | Pay/reverse the excess or explain within 7 days |
If you don't respond, you may be blocked from filing the next GSTR-1 until you do.
Practical Example
Meera's Lucknow-based handicraft business reports ₹12,00,000 of B2B sales in GSTR-1 for August 2026. While preparing GSTR-3B, her accountant notices that one ₹1,00,000 invoice was reported in GSTR-1 at 18%, although the item moved to the 5% slab under the GST 2.0 rate changes. Because the liability field is locked in 3B, she files GSTR-1A to correct the rate before filing GSTR-3B. Her 3B now auto-fills the correct liability, avoiding both overpayment and a future DRC-01B.
Common Mistakes
Filing GSTR-3B first and fixing GSTR-1 later. With the hard-lock, this no longer works.
Claiming ITC from purchase bills not in GSTR-2B. This triggers DRC-01C.
Ignoring credit notes. Unreported credit notes inflate liability.
Not reviewing IMS before the 14th. Accepted-by-default invoices may include wrong entries.
Frequently Asked Questions
1. What is the main difference between GSTR-1 and GSTR-3B? GSTR-1 reports invoice-level sales details; GSTR-3B is a summary return where you claim ITC and pay tax.
2. Can I file GSTR-3B before GSTR-1? Technically the sequence is GSTR-1 first. Since GSTR-3B liability auto-fills from GSTR-1 and can't be edited, filing GSTR-1 first is essential.
3. What happens if GSTR-1 and GSTR-3B don't match? The portal may issue DRC-01B. You must pay the difference or explain it within 7 days, or your next GSTR-1 may be blocked.
4. What is GSTR-1A? An amendment facility to correct GSTR-1 details for the same period before filing GSTR-3B.
5. What is the late fee for GSTR-3B? ₹50 per day (₹20 for nil returns), subject to turnover-based caps, plus 18% interest on late tax payment.
6. How often should I reconcile GSTR-2B with my purchase register? Every month, before filing GSTR-3B.