How to do GST Return Filing in 2026? Complete Guide

May 23, 2026

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GST was launched on 1st July 2017 through a special parliament session at midnight and changed the landscape of India’s taxation system forever. A major highlight of GST was replacing taxes on multiple points, fragmented state and centre levies, with a unified tax system.

GST filing is mandatory for all Indian registered businesses as per the CGST Act 2017, State and Union Territory GST Acts. How to File GST? What’s the role of a Billing Software in timely and accurate GST Filing and Returns?

We will address these questions with a step-by-step filing process and explain how GST billing software ensures timely tax and regulatory compliance. Let’s begin.

GST underwent major changes in tax slabs and implementation process since the launch of GST 2.0 in September 2025. Check your ERP provider for updates and ensure a tax-compliant business always.

A Step-by-Step Guide for GST Return Filing, Verification, Returns, and More

GST filing and returns is crucial for claiming ITC (Input Tax Credit), avoiding penalties and interests, maintaining business credibility, preventing registration suspension, and preference for government contracts.

Here’s the process for you to follow for easy GST filing. You can also file GST returns through a billing software from Marg ERP.

Gather All Documents

Before you sit for GST filing including GSTR-1 and GSTR-3B, ensure to have all required documents including;

Sales register containing all details of outward supplies and invoices.
Purchase register containing details of all inward supplies for claiming ITC.
ITC reconciliation data (you can verify ITC via auto-populated GSTR-2B form).
Digital signature certificate for companies and LLPs.

Log in and Navigate to Dashboard

After aggregating all the required documents;

Browse and visit GST Portal.
Login with 15-digit GSTIN, username, and password.
Go to Services-Returns-Returns Dashboard.

Choose the Period of Tax Payment

Select the FY for which you intend to do GST filing and the particular Return Filing Period (Month or Quarter) from the dropdown menu.
Click on ‘Search’.

Fill and File GSTR-1 for Outward Supplies

After ‘Search,’ Select the GSTR-1 Tab.
Upload invoice-wise details of all your sales including B2B, B2C, and credit or debit notes.
Taxpayers can enter this manually or upload JSON files exported from your GST billing software.
Click generate GSTR-1 Summary to view compiled data, preview the form, submit, and file.

Reconcile Input Tax Credit

Go through your auto-populated GSTR-2B form to check your eligible input tax credit based on vendors’ filings against your own purchase invoices before GSTR-3B filing.
This process ensures the tax payer is only claiming ITC for legitimately received goods and services.

Fill and File GSTR-3B

At this step, select the GSTR-3B tab.
Enter consolidated details of sales, purchase, and eligible ITC.
GST portal auto-calculate your net tax liability.

Pay Tax and Offset Liability

Go to the Payment of Tax section.
Offset your liability via available ITC from your electronic credit ledger.
For a remaining balance, tax payers can generate a challan (PMT-06) and pay using NEFT, RTGS, or Net Banking.

Finalize GST Filing and Return

Click on the declaration box and choose the authorized signatory.
File the GST return through an Electronic Verification Code or a Digital Signature Certificate. For EVC, you will receive an OTP on your registered mobile number and email.
Save or download the Track Return Status or acknowledgement receipt for your records.

This is how you file GST returns in easy to follow steps. Now let us explore various applicable due dates for GST returns filing.

GST Return Filing Dates: Your Checklist for GST Return Filing On-Time

Here are various dates for GST filing which every taxpayer and business must know to avoid penalty or delays.

Regular Monthly Filers

GSTR-1 (Outward Supplies): 11th of the succeeding month.
GSTR-3B (Summary of Tax Liability): 20th of the succeeding month (It can vary state to state).

Quarterly Filers

GSTR-1: 13th of the month following the quarter.
GSTR-3B: 22nd or 24th of the month following the quarter.
PMT-06 (Tax Challan): 25th of the succeeding month.

Composition Scheme Taxpayers

CMP-08 (Quarterly Return and Tax Payments): 18th of the month following the quarter.

Annual Returns (FY 2025–26)

GSTR-9 (Annual Return): 31st December, 2026.
GSTR-9C (Reconciliation Statement): 31st December, 2026 (applicable for taxpayers with turnover of more than 5 crores in a year).

Final Thought

GST return filing is mandatory for businesses operating in India. It has gone through major changes since launch in 2017 and GST 2.0 announcement in September 2025. A billing software with GST compliance feature helps businesses organize data systematically, reconciling records early, using the financial reports, and navigating through the dashboard for timely updates.

We suggest exploring Marg ERP for dedicated videos on What is GST? How to file GST returns? And many more. Visit their YouTube channel now.