How to File GSTR-3B: A Step-by-Step Guide

What GSTR-3B is (and isn’t)

GSTR-3B is a self-declared summary return. Unlike GSTR-1, it doesn’t list every invoice — it reports totals: your total outward supplies, the tax on them, the input tax credit you’re claiming, and the net tax you pay. It’s the return where money actually moves.

It must be filed for every tax period, even a period with no activity (a Nil return). Filing GSTR-3B is separate from filing GSTR-1; you generally need both.

Before you start: what to keep ready

• Total taxable sales for the period, split by tax rate
• Any zero-rated (export) and exempt/nil-rated supplies
• Your purchase records and, crucially, your GSTR-2B for the period
• Details of any supplies under reverse charge
• Your login and, for payment, funds in the electronic cash ledger or a way to pay the challan

Table 3.1 — outward supplies and reverse charge

This is where you declare your sales. You enter total taxable value and the IGST/CGST/SGST on it, plus separate rows for zero-rated, nil-rated/exempt, and inward supplies liable to reverse charge. Getting the taxable value and the tax split right here is what determines your output liability.

Table 4 — eligible input tax credit

Table 4 is where you claim ITC — and where most money is won or lost. You report credit available (largely driven by your GSTR-2B), then reverse any ineligible or blocked credit, to arrive at net ITC. The golden rule: claim what genuinely appears in 2B and is eligible; don’t over-claim on invoices your supplier hasn’t filed, or you risk interest and reversal later.

Tables 5–6 — exempt supplies and tax payment

After ITC, the return computes your net tax: output tax minus eligible ITC. Any balance is paid by creating a challan and paying into the electronic cash ledger, or offset from the credit ledger. You cannot file GSTR-3B until the liability is fully discharged — so payment and filing happen together.

Filing and the common mistakes

Once tax is paid, you submit and file with DSC or EVC. The mistakes we most often fix:

• Over-claiming ITC beyond GSTR-2B — the top cause of later notices
• Forgetting reverse-charge liability in Table 3.1(d)
• Mismatch between GSTR-1 sales and GSTR-3B sales for the same period
• Missing the Nil return in a no-activity month, triggering late fees
• Filing GSTR-3B but forgetting GSTR-1 (or vice versa)