GST Login & GSTR-1 Filing Step-by-Step Guide 2026
Quick Overview
GSTR-1 is your outward supplies return—the first return in the GST filing cycle. Every invoice you issue goes here. Your buyer's GSTR-2A is auto-populated from your GSTR-1, so accuracy matters.
Filing Deadlines 2026:
- Monthly Filers: 11th of next month
- Quarterly Filers (QRMP): 13th of month after quarter ends
Estimated Reading Time: 25 minutes | Difficulty: Easy for freshers, routine for professionals
Step 1: GST Portal Login - Complete Instructions
Before You Start
Have ready:
- Your 15-digit GSTIN (Goods and Services Tax Identification Number)
- Registered email address or User ID
- Your GST portal password
- 2FA mobile number linked to your GSTIN
How to Log In to GSTN Portal
[SCREENSHOT: GSTN Portal Login Page - Show https://www.gst.gov.in homepage with Login button]
-
Visit the GST Portal
- Go to www.gst.gov.in in your web browser
- Click "Login" in the top-right corner
-
Enter Your Credentials
- GSTIN/UIN: Enter your 15-digit GSTIN (the unique ID assigned after GST registration)
- User ID: Enter your registered email address or custom User ID
- Password: Enter your GST portal password
[SCREENSHOT: GST Login Form - Show GSTIN field, User ID field, Password field, Login button]
-
Two-Factor Authentication (2FA)
- The portal sends an OTP (One-Time Password) to your registered mobile number
- Enter the 6-digit OTP in the prompt box
- Click "Submit" or "Verify"
[SCREENSHOT: OTP Verification Screen - Show OTP input field with "Enter 6-digit OTP" label]
-
Dashboard Access
- Once verified, you'll see your GST Dashboard
- Look for "Services" or "File Return" menu on the left sidebar
- Select "File GSTR-1" to begin
[SCREENSHOT: GST Portal Dashboard - Show main dashboard with menu options, Services highlighted, GSTR-1 option visible]
Forgot Your Password?
- On the login page, click "Forgot Password"
- Enter your GSTIN or User ID
- Verify via OTP sent to registered mobile
- Create a new strong password (min 12 characters with numbers & symbols)
- Click "Update Password" and log in with new credentials
Step 2: Navigate to GSTR-1 Filing Section
Once logged in:
[SCREENSHOT: Navigation Path - Show Menu > Services > File Returns > GSTR-1]
- From dashboard, click "Services" (left sidebar)
- Select "Returns" → "File GSTR-1"
- Choose Assessment Year (e.g., 2026-27 for FY 2025-26)
- Click "Prepare Offline" or "File Now" depending on your data readiness
Pro Tip for Freshers: If you have many invoices, use "Prepare Offline" to fill in Excel, then upload bulk. For small businesses (< 50 invoices), fill directly online.
Step 3: Understanding GSTR-1 Tables & Tabs
GSTR-1 has 13 tables. Not all apply to your business. Here's a quick guide:
Business Type & Applicable Tables
B2B (Business to Business) Sales
For invoices issued to other registered GST businesses
Tables to Fill:
- Table 4A: B2B invoices (normal supply)
- Table 4B: B2B invoices with missing GSTIN (if applicable)
- Table 5A: Credit/Debit notes (if adjustments made)
- Table 12: HSN Summary (aggregate of all sales)
[SCREENSHOT: Table 4A - Show GSTR-1 Table 4A entry form with Invoice No., Date, GSTIN, Amount, Tax columns]
HSN Code Entry (Required for all):
- What: 6-digit HSN (Harmonized System of Nomenclature) code for your product/service
- Where: Column "HSN Code" in Table 4A
- Example:
- Garments → 6204 (Women's trousers)
- Software services → 6203 (IT consulting)
- Stationery → 4820 (Printed matter)
- Find yours: Search "HSN code" + your product on www.gst.gov.in
[SCREENSHOT: HSN Search on GST Portal - Show search results with code, description, GST rate]
Step 4: How to Fill GSTR-1 (Line-by-Line Instructions)
For B2B Invoices (Table 4A - Most Common)
[SCREENSHOT: Blank GSTR-1 Table 4A 1 entry - Show all columns clearly labeled]
| Column | What to Enter | Example | Notes |
|---|---|---|---|
| Sl. No. | Serial number | 1, 2, 3... | Auto-filled; just count entries |
| Invoice No. | Your invoice number | INV-2026-0001 | Must match your actual invoice |
| Invoice Date | Date you issued invoice | 15-Jun-2026 | Must be within filing period |
| GSTIN | Buyer's 15-digit GSTIN | 36AABCT1234H1Z0 | If you don't have GSTIN, use Table 4B (see below) |
| Invoice Value | Total amount before GST | ₹10,000 | Don't include GST amount here |
| Taxable Amount | Amount on which GST applies | ₹10,000 | Usually same as Invoice Value |
| SGST | State GST you collected | ₹900 (at 9%) | 9% for SGST (half of 18% rate) |
| CGST | Central GST you collected | ₹900 | 9% for CGST (half of 18% rate) |
| IGST | Integrated GST (inter-state) | ₹1,800 OR ₹0 | Use IGST if buyer is in different state; OR use SGST+CGST if same state |
| CESS | Additional tax (if applicable) | ₹200 | Only for luxury goods, coal, etc. |
| HSN Code | Product/service classification | 6204 (garments) / 6203 (IT services) | 6-digit mandatory code |
[SCREENSHOT: Filled Table 4A Entry - Show example with all columns filled with sample data]
Example Calculation (18% GST)
Scenario: You sold goods to another registered business:
- Invoice Value: ₹10,000
- HSN Code: 6204 (Garments)
- Within same state (Telangana)
- GST Rate: 18%
How to Fill:
- Invoice Amount: ₹10,000
- Taxable Amount: ₹10,000
- SGST: ₹900 (10,000 × 9%)
- CGST: ₹900 (10,000 × 9%)
- IGST: ₹0 (not applicable for intra-state)
- Total Tax: ₹1,800
- Final Invoice to Customer: ₹11,800 (10,000 + 1,800)
What If Buyer Doesn't Have GSTIN?
Use Table 4B (B2B with missing GSTIN):
- Enter invoice details same as Table 4A
- GSTIN field: Leave blank or enter "UNREGISTERED"
- GST treatment: Same as Table 4A (you still charge GST)
- Risk: No ITC benefit for buyer; may attract GST notice
[SCREENSHOT: Table 4B Entry - Show form with GSTIN blank/UNREGISTERED, warning message highlighted]
Tip: Always request GSTIN from buyers. If they're registered and claim no GSTIN, flag it.
Step 5: HSN Code Selection (Critical for Compliance)
Why HSN Codes Matter
✅ Affects your GST audit: Mismatched HSN codes trigger Department queries ✅ Determines ITC eligibility: Buyer needs matching HSN to claim ITC ✅ Tax rate verification: Wrong HSN = wrong tax rate = penalties
How to Find Your HSN Code
Method 1: Official GST Portal Search
- Go to www.gst.gov.in
- Click "Services" → "Search" → "Search HSN Code"
- Enter your product description (e.g., "Ladies Trousers", "Software Development")
- Portal returns 6-digit code, description, and applicable GST rates
- Copy the code; use it in Table 12 (HSN Summary)
[SCREENSHOT: GST Portal HSN Search - Show search bar, result list with code, description, rates]
Method 2: Common HSN Codes by Business Type
| Business Type | Product/Service | HSN Code | GST Rate |
|---|---|---|---|
| Retail / E-commerce | Electronics (Mobile, Laptop) | 8517 | 18% |
| Fashion (Garments, Shoes) | 6204/6203 | 5-12% | |
| Books, E-Books | 4901 | 0% | |
| Services | Software Development | 6203 | 18% |
| Consulting | 6202 | 18% | |
| Training | 8520 | 18% | |
| Manufacturing | Steel Products | 7208 | 0-5% |
| Chemicals | 2901 | 5% | |
| Food & Beverage | Processed Food | 2009 | 5-18% |
| Restaurant Services | 5963 | 5% |
Pro Tip: Document your HSN code once. Use it consistently across all invoices. If product changes, update HSN.
Step 6: Table 12 - HSN Summary (Aggregate View)
What is Table 12? Sum of all HSN codes used across Tables 4A, 5B, 5C, etc. Portal auto-calculates this when you add line items.
[SCREENSHOT: Table 12 HSN Summary - Show auto-populated summary with HSN codes, total value, tax by rate]
Example for Multi-Product Business:
| HSN Code | Description | Total Value | SGST 9% | CGST 9% | IGST 18% |
|---|---|---|---|---|---|
| 6204 | Ladies Trousers | ₹40,000 | ₹3,600 | ₹3,600 | ₹0 |
| 6209 | T-Shirts | ₹25,000 | ₹2,250 | ₹2,250 | ₹0 |
| Total | All Products | ₹65,000 | ₹5,850 | ₹5,850 | ₹0 |
The portal auto-populates Table 12 from your individual entries. No manual action needed unless you spot errors.
Step 7: Upload & File Your GSTR-1
Option A: Direct Online Filing (Small Businesses)
- Fill all tables directly in portal
- Review each entry for accuracy
- Click "Save" → "Submit"
- Generate "Provisional ID" (PRN) - save this
- Done - Filing complete within 2 minutes
[SCREENSHOT: GSTR-1 Submit Confirmation - Show success message with PRN number, filing date/time]
Option B: Offline File Upload (Large Businesses)
For businesses with 100+ invoices:
- Download "Excel Template" from portal
- Fill invoice details in Excel (one row = one invoice)
- Column A: Invoice No.
- Column B: Invoice Date
- Column C: GSTIN
- ... (same columns as Table 4A)
- Save as .csv or .xlsx
- Go to portal → "Upload"
- Select your file → "Validate"
- Fix any errors shown in validation report
- Re-upload corrected file
- Click "Submit" once validation passes
[SCREENSHOT: Excel Template - Show first 5 rows with headers and sample data]
[SCREENSHOT: Upload Progress - Show file validation message, success/error indicators]
Validation Checks Before Submitting
✓ All GST rates correct for product/service
✓ HSN codes match your business type
✓ Invoice dates fall within the filing period (1st to last date of month)
✓ GSTIN format correct (15 digits, no spaces)
✓ Tax calculation correct (no manual math errors)
✓ Credit/Debit notes linked to original invoices
Pro Tip: If system shows "No errors", take a screenshot before submitting. File in portal always keeps a copy, but your backup helps with reference.
Step 8: After Filing - What Happens Next?
Timeline
| When | What | Your Action |
|---|---|---|
| Day 1 | You file GSTR-1 | Portal shows "Filed" status |
| Day 1-2 | System validates entries | Errors appear in "Message" section |
| Day 2-10 | Buyer's GSTR-2A auto-populated | Buyer sees your invoices on their account |
| Day 11 | Buyer files GSTR-2 | System matches your GSTR-1 vs their GSTR-2 |
| Day 15 (next month) | Deadline to file GSTR-3B | You claim ITC and pay net GST |
[SCREENSHOT: Post-Filing Dashboard - Show filing status, PRN, can still amend indicator]
If You Make a Mistake After Filing
✓ Can amend: Use "GSTR-1A" to add/modify invoices (file anytime before GSTR-3B deadline)
✗ Cannot change: Cannot delete already-filed invoices in original GSTR-1
[SCREENSHOT: GSTR-1A Amendment Form - Show form with original invoice reference, modified values]
Step 9: Common Mistakes & How to Avoid Them
| Mistake | Impact | How to Avoid |
|---|---|---|
| GSTIN format wrong | Buyer can't claim ITC | Copy-paste GSTIN from invoice exactly |
| HSN code incorrect | Audit query, possible penalty | Cross-check with GST portal search |
| Tax rate wrong | ITC mismatch, notice | Use GST Council rate table (5%, 12%, 18%, 28%) |
| Invoice not dated | System rejects entry | Always write invoice date before issuing |
| Invoice date outside period | Invoice rejected | Only file invoices from 1st to last date of month |
| B2B missing GSTIN | Buyer can't claim ITC | Collect GSTIN at time of sale; use Table 4B only if genuinely unregistered |
| Decimal amount entries | System rejects | Ensure amounts are in ₹ (rupees), whole numbers |
Checklist: Before You File GSTR-1
- All invoices issued in the period accounted for
- Buyer GSTIN verified (15 digits, format: XX000XXXXXOXZ)
- HSN codes selected for all products/services
- Tax rates verified (5%, 12%, 18%, 28%, or 0% for zero-rated)
- Credit/Debit notes linked to original invoices
- Export invoices marked with Shipping Bill No. (if applicable)
- B2C sales aggregated by tax rate (not individual line items)
- No duplicate invoices listed
- Portal login working; password reset done if needed
- Offline file validated before upload (if uploading Excel)
FAQ - GSTR-1 Filing
Q: Can I file GSTR-1 late?
A: Yes, but ₹50/day late fee applies (₹25 CGST + ₹25 SGST) up to capped amount. File within 11 days of month-end to avoid.
Q: What if my buyer doesn't have GSTIN?
A: They're likely unregistered (turnover < ₹40 lakh). File in Table 4B. They can't claim ITC. Some states/businesses must register even below threshold—flag for verification.
Q: How do I amend a filed GSTR-1?
A: Use GSTR-1A (amendment form). Add missing invoices or correct amounts. File before month-end of next month.
Q: What's HSN code for services?
A: Services are 5-digit SAC codes, not HSN. Example: SAC 6202 for consulting. GST portal searchable under "SAC Code" tab.
Next Steps
✅ Filed GSTR-1? Now file GSTR-2 (purchases) by month-end
✅ Reconcile with buyer's GSTR-3B
✅ File GSTR-3B by deadline (20th for monthly filers)
✅ Make GST payment on same day
Need help? Contact us via WhatsApp or email. We handle GSTR-1 filing for 500+ businesses monthly—zero errors, zero penalties.
