GSTR-3B vs GSTR-1: Differences, Due Dates & Reconciliation
Every GST-registered taxpayer in India must file at least two key returns each month or quarter: GSTR-1 and GSTR-3B. While both relate to outward supplies, they serve different purposes and mismatches between them can trigger notices from the GST department. Understanding GSTR-3B vs GSTR-1 clearly is essential for clean compliance in FY 2026-27.
What Is GSTR-1?
GSTR-1 is a statement of outward supplies. It is a detail-level return where you report every invoice, credit note, and debit note issued to your customers during the period. The data filed in GSTR-1 flows into your buyer's GSTR-2B, which is the auto-drafted input tax credit (ITC) statement. Accuracy in GSTR-1 directly affects your buyers' ability to claim ITC.
- Reports invoice-level details of sales
- Includes B2B, B2C, exports, nil-rated, and exempt supplies
- Amendments to past invoices are also reported here
- No tax payment is made through GSTR-1
What Is GSTR-3B?
GSTR-3B is a summary self-declaration return. It captures the consolidated figures of outward supplies, ITC claimed, and the net GST liability payable for the period. Unlike GSTR-1, GSTR-3B involves actual tax payment. It is not an invoice-level return; you report totals under broad heads.
- Summary of outward and inward supplies (aggregate figures)
- ITC availed breakup: IGST, CGST, SGST, and Cess
- Net tax liability computed and paid here
- Reversal of ITC (e.g., under Rule 42/43) is also disclosed
Key Differences: GSTR-3B vs GSTR-1
| Parameter | GSTR-1 | GSTR-3B |
|---|---|---|
| Nature | Detail return (invoice-level) | Summary return (consolidated) |
| Purpose | Reporting outward supplies | Tax payment and ITC claim |
| Tax Payment | No | Yes |
| ITC Details | Not applicable | Yes, ITC availed and reversed |
| Impact on Buyer | Feeds buyer's GSTR-2B | No direct impact on buyer |
| Filing Frequency | Monthly or quarterly (QRMP) | Monthly or quarterly (QRMP) |
| Amendment | Possible in subsequent GSTR-1 | Limited; no direct amendment return |
Due Dates for FY 2026-27
The due dates below apply to regular taxpayers. Taxpayers under the QRMP (Quarterly Return Monthly Payment) scheme file GSTR-1 quarterly but pay tax monthly using Form PMT-06.
Monthly Filers
- GSTR-1: 11th of the following month
- GSTR-3B: 20th of the following month (for taxpayers with aggregate turnover above ₹5 crore); 22nd or 24th for smaller taxpayers in specified states under QRMP
QRMP Scheme Filers
- GSTR-1 (quarterly): 13th of the month following the quarter
- GSTR-3B (quarterly): 22nd or 24th of the month following the quarter, depending on the state category notified by CBIC
Note: Always verify the latest due dates on the official GST portal (gst.gov.in) as the government may notify extensions.
Why Reconciliation Between GSTR-1 and GSTR-3B Matters
The GST department's system automatically compares the outward supply figures declared in GSTR-1 with those in GSTR-3B. A significant mismatch can result in a GSTIN scrutiny notice under Section 61 of the CGST Act or demand proceedings. Common reasons for mismatch include:
- Invoices uploaded in GSTR-1 but turnover understated in GSTR-3B (or vice versa)
- Credit notes adjusted in GSTR-1 but not reflected correctly in GSTR-3B
- Advances received reported in GSTR-3B but invoices not yet uploaded in GSTR-1
- Amendments made in subsequent GSTR-1 not updated in the corresponding GSTR-3B period
How to Reconcile GSTR-1 and GSTR-3B
Follow these practical steps each period before filing:
- Step 1: Download the GSTR-1 filed summary and the GSTR-3B filed return for the same period from the GST portal.
- Step 2: Compare Table 3.1 of GSTR-3B (outward taxable supplies) with the total taxable value and tax in your GSTR-1.
- Step 3: Identify line items causing the difference — advances, credit notes, exempt supplies.
- Step 4: Correct differences by amending GSTR-1 in the next filing period or adjusting GSTR-3B figures with proper justification in your records.
- Step 5: Maintain a monthly reconciliation worksheet as audit evidence.
Late Fees and Consequences
Late filing of GSTR-3B attracts a late fee of ₹50 per day (₹25 CGST + ₹25 SGST) for returns with tax liability, and ₹20 per day (₹10 CGST + ₹10 SGST) for nil returns, subject to the maximum caps notified by CBIC from time to time. Interest at 18% per annum is also charged on outstanding tax. Use KyaTax's GST Late Fee Calculator to quickly estimate your late fee exposure before filing a delayed return.
Try the related KyaTax tool — fast, affordable and self-service.
Open GST Late Fee Calculator →Frequently asked questions
What is the main difference between GSTR-1 and GSTR-3B?
GSTR-1 is a detailed, invoice-level statement of outward supplies that feeds into your buyers' ITC records. GSTR-3B is a summary self-declaration return through which you actually pay your net GST liability and declare ITC availed. GSTR-1 does not involve tax payment, whereas GSTR-3B does.
Which return should be filed first — GSTR-1 or GSTR-3B?
For monthly filers, GSTR-1 is due on the 11th and GSTR-3B on the 20th of the following month, so GSTR-1 is filed first. This sequence ensures that the invoice data is available in buyers' GSTR-2B before they file their own GSTR-3B. Under the QRMP scheme, GSTR-1 (quarterly) is due on the 13th and GSTR-3B on the 22nd or 24th of the month following the quarter.
What happens if there is a mismatch between GSTR-1 and GSTR-3B?
The GST department's system flags differences between outward supply figures in GSTR-1 and GSTR-3B. A significant mismatch can lead to a scrutiny notice under Section 61 of the CGST Act, demand for differential tax, interest, and penalties. It is advisable to reconcile both returns every period and maintain supporting records explaining any genuine differences such as advances or amendments.
Related: All tools · More guides