How to file GST returns online yourself: GSTR-1 and GSTR-3B step by step

Filing GST returns yourself is straightforward when your invoices are in order and your purchases match what suppliers reported. This guide follows the monthly sequence on the GST portal.

What you need before you start

• GSTIN and portal login
• A list of all sales invoices for the period, including credit and debit notes
• Your purchase invoices, and the GSTR-2B auto-drafted statement for the month
• Details of tax already paid by cash or credit ledger
• A DSC (companies and LLPs) or your registered mobile number for EVC

The monthly sequence

Return	What it reports	Monthly due date
GSTR-1	Sales (outward supplies)	11th of the next month
GSTR-3B	Summary, input tax credit and tax payment	20th of the next month
GSTR-9	Annual return	31 December after the year

Taxpayers on the quarterly scheme (QRMP) file GSTR-1 by the 13th and GSTR-3B by the 22nd or 24th of the month after the quarter, and pay tax monthly through challan by the 25th. See the compliance calendar for the full list.

Filing GSTR-1

1. Log in and go to Services, Returns, Returns Dashboard. Choose the period and open GSTR-1.
2. Add invoices: B2B invoices to registered buyers, B2C sales, exports, credit and debit notes, and nil-rated or exempt supplies. You can upload them from a JSON file produced by accounting software or key them in.
3. Fill the HSN summary with the right HSN or SAC codes and quantities.
4. Preview the draft and check totals against your books.
5. Submit, then file with DSC or EVC. After filing you cannot edit that month's GSTR-1.

Filing GSTR-3B

1. Open GSTR-3B for the period. Values auto-populate from GSTR-1 and GSTR-2B where available.
2. Check table 3.1 (outward supplies), 3.2 (inter-state supplies to unregistered buyers), 4 (input tax credit) and 5 (exempt, nil and non-GST inward supplies).
3. Claim input tax credit only on invoices that appear in GSTR-2B and meet the conditions.
4. Pay the tax from your electronic credit ledger first, then from the cash ledger for the balance.
5. Submit, and file with DSC or EVC.

Mistakes that cost money

• Claiming credit that does not appear in GSTR-2B. This invites notices from the department.
• Mismatch between GSTR-1 and GSTR-3B. The department's system flags differences in the tax you reported on sales.
• Wrong HSN or place of supply. This sends CGST and SGST where IGST belonged, or the reverse.
• Waiting for the 20th. Portal slowdowns near the due date make late filing more likely.

Late fee and interest

A late return attracts a fee of ₹50 per day, split equally between CGST and SGST, or ₹20 per day for a nil return, up to a cap that depends on the return and turnover. Interest at 18% a year applies on any tax paid after the due date. Both continue until you file and pay.

Fixing a mistake

• GSTR-1: correct it in the amendment tables of a later GSTR-1.
• GSTR-3B: adjust it in a later month's GSTR-3B. It cannot be revised.
• Excess tax paid: claim it back through a refund application or adjust it in a later return, depending on the case.

When to hand it over

Filing yourself works well for a few invoices a month. It gets harder with large invoice volumes, multiple GSTINs, reverse charge, exports or notices from the department. GSTR-1 vs GSTR-3B explains how the two returns relate, and you can add or remove tax from an amount with the GST calculator. For returns handled end to end, see GST filing.