How to File GSTR-3B: Step-by-Step Guide for Beginners

What is GSTR-3B?

GSTR-3B is a summary return introduced under Rule 61 of the CGST Rules, 2017. It requires a registered person to declare the consolidated values of outward supplies, inward supplies liable to reverse charge, eligible input tax credit, and the net tax payable for a tax period. It is not invoice-wise; you only report totals.

It is important to understand that GSTR-3B is a self-assessed return. The tax you declare and pay here must reconcile with your GSTR-1 (outward supplies) and your GSTR-2B (the auto-generated ITC statement). Any mismatch can trigger notices, interest, or restrictions on ITC.

Who must file GSTR-3B?

Every regular taxpayer registered under GST must file GSTR-3B, even if there are no transactions in a period (in which case a NIL return is filed). Composition dealers, input service distributors, non-resident taxable persons, and TDS/TCS deductors are exempt as they file other returns. Taxpayers under the QRMP (Quarterly Return Monthly Payment) scheme file GSTR-3B quarterly while paying tax monthly through PMT-06.

GSTR-3B Due Date

For taxpayers filing monthly, the GSTR-3B due date is the 20th of the following month. For example, the return for March 2026 is due by 20 April 2026.

For taxpayers under the QRMP scheme, the quarterly due date is the 22nd or 24th of the month following the quarter, depending on the state in which the taxpayer is registered. States are divided into two categories for this staggered deadline.

Missing the deadline attracts a late fee of Rs 50 per day (Rs 20 per day for NIL returns), subject to a maximum cap, plus interest at 18% per annum on the outstanding tax under Section 50 of the CGST Act.

Documents and Information You Need

Before you begin filing, keep the following ready:

• Total taxable value of outward supplies (sales) for the period
• Output GST collected, split into IGST, CGST, SGST/UTGST, and cess
• Details of inward supplies attracting reverse charge (RCM)
• Your GSTR-2B statement to determine eligible ITC
• Details of exempt, nil-rated, and non-GST supplies
• Details of zero-rated supplies (exports and SEZ supplies)
• Sufficient balance in your electronic cash ledger, or arrangements to deposit through challan

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

Step 1: Log in to the GST Portal

Visit the GST portal and log in using your GSTIN, username, and password. Navigate to Services > Returns > Returns Dashboard. Select the relevant financial year and the return period (month or quarter) and click Search.

Step 2: Select GSTR-3B

Under the GSTR-3B tile, click Prepare Online. The portal will ask a few questions, such as whether you want to file a NIL return, whether you have any outward supplies, ITC, or interest/late fee liability. Answer accurately to display only the relevant tables.

Step 3: Fill Table 3.1 — Outward Supplies and Reverse Charge

This is the heart of the return. Enter the taxable value and tax amounts under:

• 3.1(a): Outward taxable supplies (other than zero-rated, nil, exempt)
• 3.1(b): Outward zero-rated supplies (exports and SEZ)
• 3.1(c): Other outward supplies (nil-rated, exempt)
• 3.1(d): Inward supplies liable to reverse charge
• 3.1(e): Non-GST outward supplies

Note that in recent versions of the form, table 3.1.1 separately captures supplies made through e-commerce operators under Section 9(5).

Step 4: Fill Table 3.2 — Inter-State Supplies

Here you report the inter-state supplies made to unregistered persons, composition taxable persons, and UIN holders. The values here must be a subset of those already reported in 3.1.

Step 5: Fill Table 4 — Eligible ITC

This table is largely auto-populated from your GSTR-2B. Report your ITC available, then reverse any ineligible credit (such as blocked credit under Section 17(5) — for example, motor vehicles or personal expenses). The net eligible ITC is what reduces your cash payment. Always reconcile this against your purchase register and GSTR-2B before accepting the figures.

Step 6: Fill Table 5 and Table 5.1

Table 5 captures the values of exempt, nil-rated, and non-GST inward supplies. Table 5.1 records any interest and late fee payable. The portal often auto-calculates late fees based on the delay.

Step 7: Save and Proceed to Payment

Click Save GSTR-3B. Then click Proceed to Payment or Make Payment / Post Credit to Ledger. The system displays your tax liability and the available balances in your electronic credit ledger and cash ledger.

Step 8: Offset Liability

The portal will set off your liability using available ITC first, following the prescribed order of utilisation under Sections 49, 49A, and Rule 88A — IGST credit must be fully utilised before CGST and SGST credit. Any remaining liability must be paid in cash. If your cash ledger lacks balance, create a challan in Form PMT-06 and pay via net banking, NEFT/RTGS, or over the counter.

Step 9: File with DSC or EVC

Once the liability is fully offset, click Proceed to File. Tick the declaration checkbox, select the authorised signatory, and file using a Digital Signature Certificate (DSC) — mandatory for companies and LLPs — or an Electronic Verification Code (EVC) sent to your registered mobile and email. After successful filing, an ARN (Acknowledgement Reference Number) is generated.

A Practical Example

Suppose Ravi runs a stationery shop in Maharashtra. In April 2026 his intra-state sales were Rs 5,00,000 at 18% GST, generating Rs 45,000 CGST and Rs 45,000 SGST. His GSTR-2B shows eligible ITC of Rs 30,000 CGST and Rs 30,000 SGST. He reports Rs 5,00,000 in Table 3.1(a), and his ITC in Table 4. After offsetting, his net cash liability is Rs 15,000 CGST and Rs 15,000 SGST, which he pays via PMT-06 before filing.

Common Mistakes to Avoid

Claiming ITC not reflected in GSTR-2B

Under Rule 36(4) and Section 16(2)(aa), ITC can generally be claimed only if it appears in your GSTR-2B. Claiming credit on invoices your supplier has not uploaded leads to mismatches and possible reversal with interest.

Mismatch between GSTR-1 and GSTR-3B

Your outward supply figures in GSTR-3B should reconcile with GSTR-1. Persistent differences can lead to system-generated notices in Form DRC-01B and may even restrict your ability to file GSTR-1.

Forgetting reverse charge liability

Many taxpayers omit inward supplies under reverse charge in Table 3.1(d). You must pay this in cash (it cannot be set off with ITC), and you can claim the corresponding credit only in a subsequent step.

Filing without paying full tax

GSTR-3B cannot be filed unless the entire liability is offset. Attempting to file with insufficient balance fails. Plan your cash ledger funding in advance, especially before due dates when banking systems are busy.

Ignoring NIL returns

Even with zero transactions, a NIL GSTR-3B is mandatory. Non-filing attracts late fees and can block subsequent returns, as GST returns must be filed in chronological order.

Editing after submission

GSTR-3B cannot be revised once filed. Errors can only be corrected in the next period's return. Always review every table carefully before clicking Proceed to File.

Tips for Smooth Filing

Reconcile your books, GSTR-1, and GSTR-2B before opening the return. File a few days before the due date to avoid portal congestion. Maintain a monthly checklist, and keep your DSC and registered mobile number active. Using reliable GST software can auto-populate figures and flag mismatches early, reducing manual errors significantly.