How to File GSTR-1 Online: Complete Step-by-Step Guide (2025–26)
If you're a GST-registered business in India, GSTR-1 is the return you'll deal with most frequently. Every sale you make, every invoice you raise, every credit note you issue — all of it gets reported here. Yet despite how central it is to GST compliance, a surprising number of businesses file it incorrectly, miss due dates, or don't fully understand how their GSTR-1 directly affects their buyers' ability to claim Input Tax Credit (ITC).
- GSTR-1 reports all outward supplies (sales) for the period — it directly feeds your buyers' GSTR-2B and their ITC claims.
- Monthly filers (turnover above ₹5 Crore) file by the 11th; QRMP quarterly filers (up to ₹5 Crore) file by the 13th after quarter end.
- From July 2025, GSTR-3B Table 3 is hard-locked from your GSTR-1 data — errors can no longer be fixed at the GSTR-3B stage.
- Table 12 (HSN summary) must now be filed as separate B2B and B2C tabs — merging them gets the return rejected.
- Table 13 (document summary) became mandatory from May 2025 — leaving it blank blocks submission.
- A nil GSTR-1 is mandatory even with zero transactions — skipping it triggers late fees and blocks your next GSTR-3B.
This guide covers everything: what GSTR-1 is, who files it, the exact due dates for FY 2025–26, a step-by-step portal walkthrough, and the critical 2025 rule changes you cannot afford to miss.
What Is GSTR-1 and Why Does It Matter?
GSTR-1 is a monthly or quarterly return that every GST-registered supplier must file to report all outward supplies — meaning all sales and services provided during that period. It includes:
- Invoices issued to GST-registered buyers (B2B)
- Sales to unregistered buyers (B2C)
- Credit notes and debit notes
- Exports and supplies to SEZ units
- Advance receipts
Why does accuracy matter so much? Because the moment you file your GSTR-1, it auto-populates your buyers' GSTR-2B — the document they use to claim Input Tax Credit. An error in your GSTR-1 doesn't just affect you. It blocks your customers from claiming what they're owed, damaging your business relationships and your reputation as a vendor.
GST Portal — GSTR-1 filing and return dashboard
Who Must File GSTR-1?
Who Is Required to File
All regular GST-registered taxpayers must file GSTR-1, including:
- Regular taxpayers (monthly or quarterly depending on turnover)
- SEZ units and SEZ developers
- Casual taxable persons
- E-commerce operators collecting TCS under Section 52
Who Is Exempt from GSTR-1
The following categories do not file GSTR-1 and instead file their own specific returns:
| Category | Files Instead |
|---|---|
| Composition scheme taxpayers | CMP-08 (quarterly) |
| Input Service Distributors (ISD) | GSTR-6 |
| Non-resident taxable persons (NRTP) | GSTR-5 |
| TDS deductors (Govt. entities) | GSTR-7 |
| TCS collectors (e-commerce operators) | GSTR-8 |
| OIDAR service providers | GSTR-5A |
GSTR-1 Due Dates for FY 2025–26
Your filing frequency depends on your annual aggregate turnover (AATO) in the previous financial year.
| Filer Type | Turnover | Due Date |
|---|---|---|
| Monthly filer | Above ₹5 Crore | 11th of following month |
| QRMP quarterly filer | Up to ₹5 Crore | 13th of month after quarter end |
| IFF (optional monthly upload) | QRMP filers only | 13th of months 1 & 2 |
QRMP Quarter End Dates
For quarterly filers, GSTR-1 is due by the 13th of: July (Q1), October (Q2), January (Q3), and April (Q4).
What Is IFF?
The Invoice Furnishing Facility allows QRMP-scheme taxpayers to optionally upload B2B invoice details for months 1 and 2 of each quarter — so their buyers don't have to wait until the quarterly GSTR-1 to claim ITC. It's optional, but practically essential if you have large B2B clients who need monthly ITC.
What Do You Need Before Filing GSTR-1?
- Active GSTIN and valid login credentials for gst.gov.in
- All sales invoices for the period — B2B (with buyer GSTIN) and B2C
- Credit notes and debit notes issued during the period
- HSN codes for all goods/services (6-digit for B2B if turnover > ₹5 Cr)
- Export details — shipping bill numbers and port codes if applicable
- DSC or EVC for signing and filing
How Do You File GSTR-1 Online? Step-by-Step
Follow these steps on the official GST portal at gst.gov.in:
Login to gst.gov.in with your GSTIN/username and password.
Navigate to Services → Returns → Returns Dashboard, select the Financial Year and return period, then click Search.
Open the GSTR-1 tile and choose Prepare Online (or Prepare Offline to upload a JSON file).
Fill the invoice tables — Table 4 (B2B), Table 5 (large B2C), Table 6 (exports), Table 7 (B2C summary), and amendment tables 9/10/11.
Fill Table 12 — HSN Summary, using separate B2B and B2C tabs (mandatory split from April 2025).
Fill Table 13 — Document Summary, listing your invoice, credit note, and debit note serial ranges (mandatory from May 2025).
Click Preview to download the draft GSTR-1 PDF and review every figure carefully — it cannot be revised after submission.
File using your Digital Signature Certificate (DSC) or Electronic Verification Code (EVC), and save the ARN for your records.
Step 1 — Login to gst.gov.in
Enter your GSTIN/username and password. On the homepage, you can see the return filing status for your last five tax periods at a glance.
Step 2 — Navigate to Returns Dashboard
Go to Services → Returns → Returns Dashboard. Select the Financial Year and the return period (month or quarter) from the dropdown, then click Search.
Step 3 — Open GSTR-1 and Select Prepare Online
Click on the GSTR-1 tile. You'll see two options: Prepare Online (enter data directly on portal) or Prepare Offline (upload JSON). For most businesses, Prepare Online is easiest.
Step 4 — Fill the Invoice Tables
Enter data across the relevant tables:
- Table 4 — B2B invoices (with buyer GSTIN)
- Table 5 — Large B2C invoices (>₹1 lakh, inter-state)
- Table 6 — Exports
- Table 7 — B2C summary (all remaining B2C)
- Table 9/10/11 — Amendments from previous periods
Step 5 — Fill Table 12 — HSN Summary (B2B and B2C Separately)
This is the most changed table in 2025. Table 12 is now split into two tabs: one for B2B supplies and one for B2C. You cannot combine them — doing so will cause your return to be rejected. Select HSN codes from the dropdown (manual entry removed from February 2025).
Step 6 — Fill Table 13 — Document Summary (Mandatory from May 2025)
Report your invoice series — including invoices issued, credit notes, debit notes, and their serial number ranges. This table is now mandatory; leaving it blank will block submission.
Step 7 — Preview and Generate Summary
Click "Preview" to download the draft GSTR-1 PDF. Review every figure — once submitted, GSTR-1 cannot be revised. Corrections can only be made in the next period's amendment tables.
Step 8 — File with DSC or EVC
Check the declaration box, select the authorised signatory, and file using your Digital Signature Certificate (DSC) or Electronic Verification Code (EVC) — an OTP sent to your registered mobile. Save the ARN (Acknowledgement Reference Number) for your records.
What Are the 2025–26 Rule Changes You Must Know?
| Change | Effective From | Impact |
|---|---|---|
| Table 12 bifurcated: B2B & B2C separate tabs | April 2025 | Return rejected if merged |
| Table 13 (document summary) mandatory | May 2025 | Blocks filing if blank |
| HSN codes via dropdown only — no manual entry | February 2025 | Use portal HSN search |
| GSTR-3B Table 3 hard-locked from GSTR-1 data | July 2025 | Cannot fix in GSTR-3B |
| 3-year lock: old returns cannot be filed | July 2025 | Missed periods lost forever |
What Are the Common Mistakes to Avoid in GSTR-1?
- Merging B2B and B2C in Table 12 — The portal will reject the return from April 2025. Each type needs its own row.
- Wrong or missing HSN codes — Incorrect HSN codes attract penalties under Section 122 of the CGST Act and can block your buyers' ITC claims.
- Skipping nil GSTR-1 — Even with zero sales, you must file a nil return or face late fees and blocked GSTR-3B filing.
- Filing GSTR-3B before GSTR-1 — Since July 2025, GSTR-1 data locks into GSTR-3B automatically. Always file GSTR-1 first.
- Not using IFF under QRMP — If you have large B2B buyers, failing to upload invoices via IFF monthly delays their ITC, straining business relationships.
What Are the Late Fees for Missing the GSTR-1 Deadline?
Missing the GSTR-1 due date triggers automatic late fees from Day 1:
| Annual Turnover | Max Late Fee (with liability) | Max Late Fee (nil return) |
|---|---|---|
| Up to ₹1.5 Crore | ₹2,000 | ₹500 |
| ₹1.5 Crore – ₹5 Crore | ₹5,000 | ₹500 |
| Above ₹5 Crore | ₹10,000 | ₹1,000 |
The per-day rate is ₹50/day (₹25 CGST + ₹25 SGST) for returns with tax liability, and ₹20/day for nil returns — capped at the amounts above.
Late GSTR-1 also has a domino effect: your buyers cannot claim ITC on your invoices until you file, and you cannot file your own GSTR-3B for subsequent periods if GSTR-1 is pending.
GSTR-1 vs GSTR-3B — What's the Difference?
| Feature | GSTR-1 | GSTR-3B |
|---|---|---|
| Purpose | Report all outward supplies (sales) | Summary return — pay net GST |
| Detail level | Invoice-by-invoice | Consolidated totals only |
| Due date (monthly) | 11th of next month | 20th of next month |
| Can be revised? | No — amend in next period | No |
| Feeds into | Buyer's GSTR-2B (their ITC) | Tax payment ledger |
| File order | File first | File after GSTR-1 |
Think of it this way: GSTR-1 is the ledger of what you sold. GSTR-3B is the cheque you write to the government. Both are required, and the sequence matters — always GSTR-1 first.
Conclusion
GSTR-1 filing is the foundation of your GST compliance. The key actions for FY 2025–26:
Split Table 12 into B2B and B2C (non-negotiable from April 2025)
Fill Table 13 document summary every period (mandatory from May 2025)
File GSTR-1 before GSTR-3B — Table 3 is now hard-locked
Never miss a period — the 3-year lock makes old returns permanently unfixable
Set a recurring calendar reminder for the 11th (or 13th if you're on QRMP) every month. Use our GST Calculator to verify amounts before filing. And if you have complex transactions — exports, SEZ supplies, RCM purchases — consider GST filing software or a chartered accountant to avoid costly errors.
Related: Input Tax Credit Under GST · CGST vs SGST vs IGST · GST Invoice Format
How to File GSTR-1 — Frequently Asked Questions
Is GSTR-1 mandatory even with zero sales?
Yes. A nil GSTR-1 must be filed even with zero transactions in the period — skipping it attracts late fees and blocks your next period's GSTR-3B.
What is the due date for monthly GSTR-1 filers?
The 11th of the following month, for taxpayers with annual aggregate turnover above ₹5 Crore. QRMP quarterly filers have until the 13th after quarter end.
Can I correct a mistake after filing GSTR-1?
No, GSTR-1 cannot be revised once submitted. Corrections can only be made via amendment tables in the next period's GSTR-1, ideally before filing GSTR-3B since Table 3 is now hard-locked from GSTR-1 data.
What happens if I file GSTR-3B before GSTR-1?
Since July 2025, GSTR-3B's Table 3 auto-fills and locks based on your GSTR-1 data, so GSTR-1 must always be filed first to ensure the figures are correct.
Can Table 12 combine B2B and B2C HSN summaries?
No. From April 2025, Table 12 requires separate B2B and B2C tabs — merging them causes the return to be rejected.
Verify invoice GST before you file
Check the exact CGST, SGST, or IGST on any invoice before entering it into GSTR-1 — avoid mismatches that block your buyer's ITC.
Open the Free GST Calculator India →