How to File GST Returns Online: Step-by-Step Guide (2026)

Are you filing your GST returns yourself for the first time? Or do you always hand everything to your CA and want to learn how to do it yourself? Filing GST returns online is not as hard as it looks. Once you understand the process, each return takes less than 30 minutes if your invoices are organized. In this step-by-step guide, we walk you through exactly how to file GSTR-1 and GSTR-3B on the GST portal — in very simple words.

We also explain some common mistakes people make during filing so you can avoid them. By the end of this guide, you will be confident enough to file your own returns every month without depending on anyone else.

What You Need Before You Start Filing

Before you log in to the GST portal and start filing, make sure you have these things ready. This preparation will make the actual filing much faster and smoother.

First, your GST login credentials — your username (usually your GSTIN) and password for the GST portal (gst.gov.in). If you have forgotten your password, you can reset it on the portal using your registered mobile number or email. Second, a complete list of all sales invoices you issued during the month, with customer GSTIN, invoice number, date, taxable value, and GST amount. Third, a list of all purchase invoices from GST-registered suppliers, for claiming Input Tax Credit. Fourth, your GSTR-2B downloaded from the portal (available after the 14th of each month) to verify ITC. Also, it is strongly recommended to have your billing software GST summary report ready — this makes data entry on the portal much faster and almost error-free.

How to File GSTR-1 Online (Step by Step)

GSTR-1 is the form where you report all your outward sales invoices for the month. It is due on the 11th of the following month. Here is exactly how to file it.

Step 1: Log In to the GST Portal

Go to gst.gov.in on your browser. Click on “Login” in the top right corner. Enter your GSTIN as the username and your password. Also, complete the CAPTCHA verification. After logging in successfully, you will see your GST dashboard with all pending returns and notices.

Step 2: Navigate to GSTR-1

From the dashboard, click on “Services” in the top menu. Then click on “Returns.” Next, click on “Returns Dashboard.” Select the financial year and the tax period (month) for which you want to file. You will see a list of all returns for that period. Click on “Prepare Online” under the GSTR-1 section.

Step 3: Enter Your B2B Invoice Details

In GSTR-1, you need to enter your sales invoices in different sections based on the type of sale. For sales to GST-registered businesses (B2B), click on “4A, 4B, 4C, 6B, 6C — B2B Invoices.” Then click “Add Invoice” and enter the buyer’s GSTIN, invoice number, invoice date, total taxable value, and GST amount split into CGST, SGST, and IGST. Repeat this for every B2B invoice issued during the month.

Step 4: Enter B2C Sales Summary

For sales to non-registered customers (B2C), click on “5A, 5B — B2C (Large) Invoices” for invoices above ₹2.5 lakh, or “7 — B2C Others” for smaller B2C sales. For B2C others, you only need to enter a consolidated summary — not individual invoices. Also, enter the state of supply and the total taxable value and tax amounts by GST rate.

Step 5: Enter Credit Notes and Debit Notes

If you issued any credit notes or debit notes during the month, enter them in the “9B — Credit/Debit Notes (Registered)” or “9B — Credit/Debit Notes (Unregistered)” section. Enter the original invoice number, the credit/debit note number, date, and the adjustment amount. This step is important because unentered credit notes cause mismatches in your customer’s ITC.

Step 6: Preview and Submit GSTR-1

After entering all data, click “Preview” to see a summary of all your entries. Review it carefully — check that total sales match your billing software report. If everything looks correct, click “Submit.” After submission, click “File GSTR-1” and authenticate using either your EVC (electronic verification code sent to your mobile) or a DSC (digital signature certificate). Your GSTR-1 is now filed successfully.

How to File GSTR-3B Online (Step by Step)

GSTR-3B is the summary return where you pay your actual GST liability. It is due on the 20th of the following month. Always file GSTR-1 before GSTR-3B. Here is how to file GSTR-3B.

Step 1: Go to Returns Dashboard and Select GSTR-3B

Log in to gst.gov.in and go to Services → Returns → Returns Dashboard. Select the financial year and tax period. Click on “Prepare Online” under the GSTR-3B section.

Step 2: Fill in Your Outward Supplies (Table 3.1)

In Table 3.1, enter your total outward taxable supplies for the month. This must match your GSTR-1 data. Enter the total taxable value and the corresponding IGST, CGST, and SGST amounts separately. Also, enter any exempt or nil-rated supplies in the appropriate rows. Because this table directly determines your tax liability, always cross-check it with your GSTR-1 summary before entering.

Step 3: Enter Your ITC Details (Table 4)

In Table 4, enter the Input Tax Credit you are claiming for the month. Use your GSTR-2B as the source for these numbers — only claim ITC for invoices that appear in your GSTR-2B. Enter IGST, CGST, and SGST ITC separately in the correct rows. Also, do not claim ITC on blocked credits such as personal expenses, food and beverages, or motor vehicles (with some exceptions).

Step 4: Check the Net Tax Payable

After entering outward supplies and ITC, the portal automatically calculates your net tax payable. This is your total output tax minus your eligible ITC. Review this amount carefully. If it does not match your expectations, go back and check your entries before proceeding. Also, check your electronic credit and cash ledger balances on the portal to see if you have existing credits to offset the liability.

Step 5: Pay the Tax and File GSTR-3B

If you have a tax liability to pay, click “Make Payment” and pay using internet banking, UPI, or NEFT/RTGS. The amount is deposited into your electronic cash ledger on the GST portal. After the payment is reflected, click “File GSTR-3B” and verify using EVC or DSC. Your GSTR-3B is now filed. Also, save or download the filing acknowledgement for your records.

Common Mistakes to Avoid When Filing GST Returns

Many people make these mistakes when filing GST returns online. Knowing them in advance will save you a lot of trouble.

The first common mistake is entering wrong GSTINs for customers in GSTR-1. If you enter a wrong GSTIN, that invoice will not appear in the correct customer’s GSTR-2B. The customer will then be unable to claim ITC and will come back to you with a complaint. Always verify your customer’s GSTIN on the GST portal before creating an invoice. The second mistake is claiming ITC in GSTR-3B for invoices that are not in GSTR-2B. This is flagged automatically by the system and can lead to a notice. Third, many people forget to save their entries while working on the portal. The GST portal does not always auto-save. Therefore, click “Save” frequently while entering data to avoid losing your work.