How To Fill GST Return: 2026 Zero-Error CEO Playbook

Key Takeaways

• GSTR-1 (outward supplies declaration) is due by the 11th of the following month for monthly filers, no tax payment required in this form
• GSTR-3B (summary return and tax payment) is due by the 20th of the following month for businesses with turnover above ₹5 crore
• QRMP taxpayers (turnover up to ₹5 crore) file quarterly: GSTR-1 due by the 13th, GSTR-3B due by the 22nd or 24th after quarter-end
• You need your GSTIN, all sales invoices, purchase invoices, and your GSTR-2B reconciliation ready before you start
• ITC on motor vehicles (passenger cars), food, health clubs, and construction of immovable property is blocked under Section 17(5) of the CGST Act — do not claim it
• Late fee is ₹50 per day for taxable returns, nil returns also attract a ₹20 per day late fee — there is no exemption for zero transaction months
• GST returns cannot be revised — errors are corrected only through amendment tables in the following period's return
• Always file GSTR-1 before GSTR-3B for the same period

What Is A GST Return And Which One Do You Need To File?

A GST return is a formal document you submit on the GST portal declaring your outward supplies, inward supplies, tax liability, and Input Tax Credit, for a given period. Every GST-registered business must file returns, including businesses with zero transactions in that period. A nil return is still mandatory.

The gst return filing process varies depending on your taxpayer category:

• Regular taxpayers with turnover above ₹5 crore: GSTR-1 monthly and GSTR-3B monthly
• Regular taxpayers with turnover up to ₹5 crore (QRMP scheme): GSTR-1 quarterly and GSTR-3B quarterly, with optional Invoice Furnishing Facility in the first two months of each quarter for B2B invoices
• Composition scheme dealers (turnover up to ₹1.5 crore): CMP-08 quarterly and GSTR-4 annual
• Input Service Distributors: GSTR-6
• E-commerce operators: GSTR-8
• Non-resident taxable persons: GSTR-5
• Annual return (GSTR-9): Mandatory for businesses with turnover above ₹2 crore, optional below ₹2 crore

The two returns that cover most Indian businesses are GSTR-1 and GSTR-3B. This guide focuses on these two.

Registration thresholds: You must register for GST, and therefore file returns, if your aggregate turnover exceeds ₹40 lakh for goods or ₹20 lakh for services. For special category states, the threshold is ₹10 lakh.

What You Need Before You Start Filing

Trying to file without all your data ready is a reliable way to make errors that haunt you for months. GST returns cannot be revised, only amended in a future period. Get this together before you open the portal.

Portal access:

• Your GSTIN and login credentials for gst.gov.in
• DSC if your business is a company, EVC via OTP for proprietors, partnerships, and LLPs

Sales data:

• All B2B invoices for the period, each one needs buyer's GSTIN, invoice number, date, taxable value, and CGST or SGST or IGST breakup
• All B2C invoices, consolidated for small transactions, invoice-wise for inter-state transactions above ₹2.5 lakh
• Credit notes and debit notes issued during the period
• Advance receipts for services, GST is payable on advances at the time of receipt under Section 13(2) of the CGST Act

Purchase data:

• All inward supply invoices from which you plan to claim ITC, supplier GSTIN, invoice number, date, and tax paid
• Your GSTR-2B, the auto-drafted ITC statement generated on the 14th of every month. This is your reconciliation baseline. Do not claim ITC that does not appear in GSTR-2B without first following up with your supplier to get their GSTR-1 corrected

HSN or SAC summary:

• Turnover above ₹5 crore: report HSN codes at 6 digit level
• Turnover between ₹1.5 crore and ₹5 crore: 4 digit level
• Below ₹1.5 crore: 4 digit level for B2B

Practical tip: Export your sales register and purchase register from your accounting software in a format matching the GST portal structure. This prevents manual re-entry errors, especially when you have 50 or more invoices in a month.

GST Return Filing Due Dates You Cannot Miss

Quarter-end months: June for Q1, September for Q2, December for Q3, March for Q4.

QRMP taxpayers: Even though your GSTR-3B is quarterly, you still pay tax monthly using PMT-06 challan, due by the 25th of the following month for the first two months of each quarter.

Critical sequencing rule: Always file GSTR-1 before GSTR-3B for the same period. From July 2026 onwards, the outward liability fields in GSTR-3B are auto-populated from your filed GSTR-1 and are non-editable. If your GSTR-1 has an error, you must correct it via GSTR-1A before your GSTR-3B is filed. GSTR-3B User Guide

How To Fill GSTR-1 Step By Step

GSTR-1 is a declaration of all your outward supplies. It does not require any tax payment, it is purely a reporting form. It directly affects your buyers' ITC claims, so accuracy here matters.

Step by step on the portal:

Step 1: Log in to gst.gov.in → Services → Returns → Returns Dashboard → Select Financial Year and Return Filing Period → Click "Prepare Online" under the GSTR-1 tile. beaconfiling.com

Step 2 — Table 4, B2B Invoices: Enter every invoice raised to a GST-registered buyer. Required fields: receiver's GSTIN, invoice number, invoice date, invoice value, place of supply, taxable value, applicable tax rate, and the CGST or SGST or IGST split. These entries auto-populate your buyer's GSTR-2B.

Step 3 — Table 5, B2C Large Invoices: Inter-state B2C invoices above ₹2.5 lakh must be reported individually with the recipient's state.

Step 4 — Table 6, B2C Small, Consolidated: All intra-state B2C sales and inter-state B2C invoices below ₹2.5 lakh are reported as a consolidated, state-wise summary.

Step 5 — Table 7, Nil or Exempt or Non-GST Supplies: Report supplies attracting 0% GST or those outside the GST net.

Step 6 — Table 8, Zero Rated Supplies, Exports And SEZ: Declare exports and SEZ supplies. If exporting under LUT, select without payment of tax. If paying IGST on exports and claiming refund, select with payment of tax.

Step 7 — Table 9, Amendments: If you need to correct an invoice from a previous period, do it here, not by refiling the previous period's GSTR-1.

Step 8 — Table 11, Advances: Service businesses must declare advances received on which GST is payable before the invoice is raised.

Step 9 — Table 12, HSN Summary: Mandatory for all filers. Enter the HSN or SAC codes, description, unit of measurement, quantity, taxable value, and tax amounts for all outward supplies aggregated by code.

Step 10: Preview the return by downloading the PDF draft. Cross-check totals against your sales register. Then Submit → File using DSC or EVC.

Important: Once GSTR-1 is filed, it cannot be deleted or revised. Errors in a filed GSTR-1 must be corrected using GSTR-1A before your GSTR-3B is processed. From July 2026, GSTR-3B pulls liability directly from GSTR-1.

How To Fill GSTR-3B Step By Step

GSTR-3B is a self-assessed summary return where you declare your net tax liability and pay it. Think of it as the return that settles the account.

Step 1: Log in to gst.gov.in → Services → Returns → Returns Dashboard → Select period → GSTR-3B → Prepare Online. tutorial.gst.gov.in

Step 2 — Table 3.1, Outward And Reverse Charge Supplies: From July 2026, this table is auto-populated from your filed GSTR-1 and is non-editable. Key rows are 3.1(a) outward taxable supplies, 3.1(b) zero rated, 3.1(c) nil or exempt or non-GST outward supplies, 3.1(d) inward supplies under RCM, and 3.1(e) non-GST outward supplies.

Step 3 — Table 3.2, Inter State Supplies: Report inter-state B2C and supplies to composition or unregistered buyers by state.

Step 4 — Table 4, ITC Available: Declare the ITC you are claiming this period. 4(A)(5) for all other inward supplies, 4(A)(1) and 4(A)(2) for imports, 4(A)(3) for ITC on inward supplies under RCM, 4(B) for ITC reversed, and 4(D) for ineligible ITC under Section 17(5). Reconcile against GSTR-2B before entering numbers. accountune.com

Step 5 — Table 5, Exempt Inward Supplies: Purchases that do not carry any ITC go here.

Step 6 — Table 6, Payment Of Tax: The portal computes your net liability. The system first uses your Electronic Credit Ledger to offset liability. Any remaining balance must be paid from your Electronic Cash Ledger by creating a challan, paying via net banking or NEFT or RTGS, then returning to GSTR-3B to complete filing.

Step 7: Verify all values, preview, and file with DSC or EVC. You receive an ARN, your proof of filing.

How To File GST Return Online — The Full Portal Walkthrough

The correct URL is gst.gov.in, not gstn.gov.in. The latter is the GSTN organisation website, not the taxpayer portal.

Login: Enter your GSTIN, username, password, and CAPTCHA. Navigate to Services → Returns → Returns Dashboard. Select the correct Financial Year and Return Filing Period.

Three ways to enter your data:

1. Prepare Online: Enter invoice data directly on the portal, practical for businesses with under 100 invoices per month
2. Offline Tool: Download the GST Offline Tool from the portal, fill the Excel-based utility, generate a JSON file, and upload it, best for high volume
3. API-based filing: If you use accounting software with GSTN API integration, your invoices sync directly to the portal

Verification methods: EVC via OTP for sole proprietors, partnerships, and LLPs. DSC is mandatory for companies, and for LLPs above ₹100 crore turnover.

After filing: An ARN is generated immediately and sent to your registered email and mobile. This ARN is your compliance record.

One hard rule to remember: GST returns cannot be revised after filing. If you discover an error in a filed GSTR-1, correct it in the amendment tables of the following month's GSTR-1, not in the original period.

Late Fees, Penalties, And Interest For GST Non-Compliance

Late fee for GSTR-1 and GSTR-3B:

• ₹50 per day of delay for returns with tax liability
• ₹20 per day for nil returns
• Maximum cap: ₹10,000 per return for regular taxpayers, with lower caps of ₹2,000 or ₹5,000 for lower turnover slabs

Interest on delayed tax payment: 18% per annum on outstanding net cash liability, 24% for excess ITC claimed or excess reduction in output tax liability.

Example: ₹1,00,000 due on 20 August, paid on 20 September, interest = ₹1,00,000 × 18% × 31/365 = ₹1,529.

Registration cancellation: If GSTR-3B is not filed for 6 consecutive months, or 3 consecutive quarters for composition dealers, the officer can cancel registration under Section 29(2).

Nil returns also attract late fees. accountune.com

Common GST Filing Mistakes And How To Avoid Them

• Mistake 1 — GSTR-1 And GSTR-3B Mismatch: Cross-check totals between both forms before filing to avoid scrutiny notices.
• Mistake 2 — Claiming Blocked ITC Under Section 17(5): Passenger cars, food and beverages, health club memberships, and immovable property works contracts are blocked.
• Mistake 3 — Wrong Place Of Supply: Charging CGST or SGST on an inter-state transaction, or IGST on an intra-state one, creates liability and ITC issues.
• Mistake 4 — Not Reconciling GSTR-2B Before GSTR-3B: ITC not in GSTR-2B is a reconciliation risk. accountune.com
• Mistake 5 — Filing GSTR-3B Before GSTR-1: From July 2026, GSTR-3B pulls figures from GSTR-1, so file GSTR-1 first and correct via GSTR-1A if needed.
• Mistake 6 — Missing Advance Receipts: For services, GST on advances is payable at receipt time under Section 13(2).
• Mistake 7 — HSN Code Errors: Wrong classification applies wrong tax rates and cascades across returns.
• Mistake 8 — Missing RCM On Imports Of Services: IGST under RCM applies to many foreign-billed cloud and ad services, and can be claimed as ITC if eligible.

DIY Filing Vs. Getting Professional Help — What Makes Sense For Your Business

DIY works if:

• You have fewer than 50 transactions per month
• You have only B2C sales
• No inter-state supplies, no RCM obligations, and simple ITC
• You can dedicate 2 to 3 hours per month and track due dates and portal changes

Get professional help when:

• You have B2B invoices
• You have multiple GST registrations across states
• You have exports or SEZ supplies
• You have RCM obligations
• Notices have started arriving, such as ASMT-10, DRC-01, or Section 73 or 74 demands

The real cost of a DIY error: A mismatch that triggers a demand under Section 73 means paying tax due, 18% interest, and a minimum penalty of ₹10,000 or 10% of tax, whichever is higher. Under Section 74, penalties can reach 100% of tax due.

What professional support costs: A CA or GST practitioner typically charges ₹1,500 to ₹5,000 per month for small business GST filing depending on volume. Full compliance suites covering GST, TDS, and accounting, such as Virtual Accounting by AI Accountant, start at ₹4,000 per month for up to 200 transactions. That fee is deductible as a business expense under Section 37 of the Income Tax Act.

If you want a CA team to handle GSTR-1, GSTR-3B, GSTR-9, and every other filing that comes with running a business, without hiring full-time finance staff, Virtual Accounting by AI Accountant covers end to end GST compliance starting at ₹4,000 per month. Learn more.

FAQ

What Happens If I File GSTR-3B Before GSTR-1 For The Same Period?

From July 2026, GSTR-3B outward liability fields are auto-populated from GSTR-1 and are locked. If GSTR-1 is not filed first, the liability figures in GSTR-3B will be absent or incorrect. Always file GSTR-1 before GSTR-3B.

Can I Revise A GST Return After Filing?

No. GST returns cannot be revised. Errors in a filed GSTR-1 must be corrected through the amendment tables in the next period's GSTR-1, or via GSTR-1A before your GSTR-3B is processed. GSTR-3B errors are corrected in the following month's GSTR-3B.

What Is The Difference Between GSTR-2A And GSTR-2B?

GSTR-2A is a dynamic view that updates as suppliers file. GSTR-2B is a static, monthly, auto-drafted ITC statement generated on the 14th of each month. For ITC claim purposes, GSTR-2B is authoritative for the period.

Do I Need To File A GST Return Even If I Had Zero Sales In A Month?

Yes. A nil GSTR-3B is mandatory. Failing to file attracts ₹20 per day in late fees. Continued non-filing can lead to registration cancellation under Section 29(2).

What Is The QRMP Scheme And Is It Beneficial?

The Quarterly Return Monthly Payment scheme is available for turnover up to ₹5 crore. You file GSTR-1 and GSTR-3B quarterly, but pay tax monthly via PMT-06 by the 25th. It reduces filing frequency while keeping tax payments current.

What Is Reverse Charge Mechanism And Who Needs To Pay It?

Under RCM, the recipient pays GST. It applies to notified categories such as import of services, legal services from individual advocates, and certain supplies from unregistered vendors. RCM tax can generally be claimed as ITC in the same period if eligibility conditions are met and the supply is for business use.

How Much ITC Can I Claim From GSTR-2B?

Claim up to the amount reflected in your GSTR-2B for the period. If you plan to claim provisional ITC beyond GSTR-2B, check the current Rule 36(4) limits and ensure supplier follow-up and documentation to mitigate reconciliation risk.

What Is An ASMT-10 Notice And How Do I Respond?

ASMT-10 is a scrutiny notice for discrepancies such as GSTR-1 versus GSTR-3B mismatches or GSTR-3B versus GSTR-2B differences. Respond within 30 days with explanations and corrections. Ignoring it can escalate to a demand under Section 73 or 74.

What Are The HSN Code Reporting Requirements For GSTR-1?

Turnover above ₹5 crore must report 6 digit HSN. Between ₹1.5 crore and ₹5 crore reports 4 digit HSN. Below ₹1.5 crore, 4 digit HSN is required for B2B invoices. Accurate HSN or SAC ensures correct tax rates and cleaner compliance.

When Should I Use The GST Offline Tool Instead Of Prepare Online?

Use the Offline Tool when you have more than 100 invoices per period, where manual entry is slow and error-prone. Download the tool from gst.gov.in, populate the Excel utility, generate JSON, and upload it. For very high volumes, consider API-based filing through software integrated with GSTN.