If you log in to the GST portal to file your monthly or quarterly summary return and encounter an error or inactive button indicating GSTR 3B not allowed GSTR 1 not filed, your outward return for the period is still pending. The portal enforces mandatory sequential filing, preventing any taxpayer from filing tax payments before declaring outward supply invoices.
The statutory rule behind the restriction
The restriction is governed by statutory provisions in the Goods and Services Tax law:
- CGST Act Section 39(10): A registered person shall not be allowed to furnish a return for a tax period if the return for any previous tax period or the details of outward supplies under Section 37 for the said tax period has not been furnished. Read the statutory text at Section 39(10), CGST Act.
- CGST Rules Rule 59(6): This rule establishes a reciprocal lock. Under Rule 59(6)(a) and (b), CGST Rules, a registered person is not allowed to furnish Form GSTR-1 or use the Invoice Furnishing Facility (IFF) if they have not furnished Form GSTR-3B for the preceding tax period.
Together, Section 39(10) and Rule 59(6) enforce an unbroken sequential loop: you cannot file current GSTR-1 without preceding GSTR-3B, and you cannot file current GSTR-3B without current GSTR-1. To understand how GSTR-3B receives these figures and balances them against input tax credit, review how GSTR-2B feeds GSTR-3B.
Common mistake: Attempting to pay tax via GSTR-3B before completing GSTR-1 to stop interest from accumulating. The portal will not permit submission of GSTR-3B until GSTR-1 is completely filed with an Electronic Verification Code (EVC) or Digital Signature Certificate (DSC).
Step-by-step order to unblock your return
When your GSTR-3B return is blocked due to unfiled GSTR-1, follow this sequence per official portal procedures:
- Check preceding returns: Confirm that GSTR-3B for all earlier months has been filed. If an earlier month GSTR-3B is pending, Rule 59(6) blocks filing current GSTR-1.
- File Form GSTR-1: Navigate to Services > Returns > Returns Dashboard. Select the financial year and return period. In the GSTR-1 tile, click Prepare Online or upload via the offline tool, generate summary, proceed to file, and submit with DSC or EVC per the official GSTN GSTR-1 User Guide.
- Generate GSTR-3B: After GSTR-1 status changes to "Filed", return to the Returns Dashboard and open the GSTR-3B tile. Auto-drafted figures from GSTR-1 populate outward tax in Table 3.1, while inward credit populates from Form GSTR-2B in Table 4 per GSTN GSTR-3B Manual.
- Offset liability and file: Verify tax liabilities, utilize eligible input tax credit, pay any cash balance via electronic cash ledger, and file GSTR-3B.
Late fee impact under Section 47
Delaying GSTR-1 and GSTR-3B triggers independent late fees under Section 47 of the CGST Act. The base statutory fee under Section 47(1) is ₹100 per day per Act up to a maximum of ₹5,000, but relief notifications reduce these amounts:
- GSTR-1 late fee: Reduced under Notification 4/2018-Central Tax to ₹25 per day under CGST (plus ₹25 per day under SGST, totaling ₹50 per day for regular liability), and ₹10 per day under CGST (plus ₹10 under SGST, totaling ₹20 per day) for nil outward supplies. Capped under Notification 20/2021-Central Tax based on turnover.
- GSTR-3B late fee: Reduced under Notification 19/2021-Central Tax to ₹25 per day under CGST (plus ₹25 per day under SGST) for regular returns, and ₹10 per day under CGST (plus ₹10 under SGST) for nil tax liability.
- Payment mechanism: Under GSTN portal rules, the late fee for delayed GSTR-1 and delayed GSTR-3B is auto-calculated and charged in Table 5.1 of the subsequent tax period's GSTR-3B return.
Worked example: sequential filing delay and late fee calculation
Consider Om Logistics, an enterprise with turnover under ₹1.5 crore in the preceding financial year. For September 2026, due dates were 11 October 2026 for GSTR-1 and 20 October 2026 for GSTR-3B. Due to internal delay, both returns are filed on 30 October 2026.
Because GSTR-3B cannot be filed without filing GSTR-1, both returns suffer delay. Here is the calculation of late fee under Notification 4/2018-CT, Notification 19/2021-CT, and Notification 20/2021-CT:
| Return form | Due date | Filing date | Days delayed | Daily rate (CGST + SGST) | Total late fee (₹) |
|---|---|---|---|---|---|
| GSTR-1 | 11 October 2026 | 30 October 2026 | 19 days | ₹25 + ₹25 = ₹50 | ₹950 |
| GSTR-3B | 20 October 2026 | 30 October 2026 | 10 days | ₹25 + ₹25 = ₹50 | ₹500 |
| Combined total | N/A | N/A | N/A | N/A | ₹1,450 |
Formula verification:
- GSTR-1 late fee: 19 days delayed × ₹50 per day = ₹950 (₹475 CGST + ₹475 SGST).
- GSTR-3B late fee: 10 days delayed × ₹50 per day = ₹500 (₹250 CGST + ₹250 SGST).
- Total statutory late fee liability across both returns: ₹950 + ₹500 = ₹1,450.
Frequently asked questions
Why does the portal block GSTR-3B when GSTR-1 is not filed?
Under Section 39(10) of the CGST Act, a registered person is not allowed to furnish a return in Form GSTR-3B for a tax period until the statement of outward supplies under Section 37 (Form GSTR-1) for that same tax period has been furnished.
Can I file GSTR-1 if the previous month GSTR-3B is pending?
No. Under Rule 59(6)(a) and (b) of the CGST Rules, a taxpayer cannot furnish Form GSTR-1 or use the IFF if the Form GSTR-3B for the preceding tax period has not been furnished.
Does late fee apply to both GSTR-1 and GSTR-3B when filing is delayed?
Yes. Late fee applies under Section 47 of the CGST Act for both GSTR-1 and GSTR-3B. The GSTR-1 late fee is auto-populated in Table 5.1 of the subsequent GSTR-3B return.
Reconcile purchases before filing GSTR-3B
Once your GSTR-1 is filed, ensure Table 4 of GSTR-3B accurately matches eligible ITC from your purchase register against GSTR-2B. Your GSTR-2B and purchase register files are read in your browser and never uploaded to any server.
Last checked: 24 October 2026. Sources: Section 39(10), CGST Act, Rule 59(6), CGST Rules, GSTN GSTR-1 User Manual, GSTN GSTR-3B User Manual.