GSTR-3B — the complete
filing guide.

What is GSTR-3B?

GSTR-3B is the monthly summary return that every regular GST taxpayer in India files. It's the return where you actually pay your GST. GSTR-1 (filed earlier in the month) reports your sales invoice-by-invoice; GSTR-3B is the consolidated, summary view from which actual tax liability is calculated and paid.

Think of GSTR-1 as the detailed sales register, and GSTR-3B as the cover page that says "here's the bottom line, here's what I owe, here's the credit I'm using." Both are mandatory and they have to agree with each other.

Who has to file it?

• Regular taxpayers — every business registered as a regular taxpayer under GST has to file GSTR-3B every month (or every quarter under QRMP — more on that below).
• Composition scheme taxpayers do not file GSTR-3B. They file CMP-08 quarterly and GSTR-4 annually instead.
• Input Service Distributors (ISD), casual taxable persons, and non-resident taxpayers have separate returns.
• Nil returns — even if you had no sales or purchases in a month, you still have to file GSTR-3B. Skipping it triggers late fees from day one.

Due dates & the QRMP scheme

Monthly filing (default)

For most taxpayers, GSTR-3B is due on the 20th of the following month. So your GSTR-3B for May is due by 20th June. Late fees and interest start accruing from the 21st.

QRMP scheme — for businesses with turnover ≤ ₹5 crore

Businesses with previous-FY turnover up to ₹5 crore can opt for the Quarterly Return, Monthly Payment (QRMP) scheme. Under QRMP:

• You file GSTR-3B quarterly — once every three months — instead of monthly.
• But you still pay tax monthly through challan PMT-06 in months 1 and 2 of the quarter.
• Quarterly due date: 22nd or 24th of the month following the quarter, depending on your state. (Southern states get 24th; rest get 22nd.)
• Monthly payment due date: 25th of the following month.

Section-by-section walkthrough

Section 3.1 — Details of outward supplies and inward supplies liable to reverse charge

This is where you declare what you sold. Five rows:

• (a) Outward taxable supplies (other than zero-rated, nil-rated, and exempt) — your normal taxable sales. Enter total taxable value plus IGST, CGST, SGST, and cess.
• (b) Outward taxable supplies (zero-rated) — exports and SEZ supplies. Taxable value only; tax rate is 0% (or you pay IGST and claim refund — declare under (a) instead).
• (c) Other outward supplies (nil-rated, exempted) — exempt and nil-rated items. Value only.
• (d) Inward supplies (liable to reverse charge) — purchases where you pay GST on behalf of the supplier (e.g., legal fees, GTA, imports). Enter taxable value plus the tax you're paying as RCM.
• (e) Non-GST outward supplies — petrol, diesel, alcohol for human consumption — items outside GST.

Section 3.1.1 — e-commerce operator supplies (notified u/s 9(5))

If you sell through Swiggy, Zomato, Ola, or similar — supplies where the platform pays GST on your behalf u/s 9(5) — declare them here. Most small businesses skip this section.

Section 3.2 — Inter-state supplies to unregistered persons, composition dealers, and UIN holders

State-wise breakdown of B2C inter-state sales. Required only if you have inter-state B2C sales. Each row = one destination state with place-of-supply, taxable value, and IGST.

Section 4 — Eligible ITC

This is the big one — your input tax credit:

• (A) ITC available (whether in full or part) — total ITC available to you for the month, broken into imports (goods), imports (services), inward supplies from ISD, inward supplies liable to RCM, and "all other ITC."
• (B) ITC reversed — credits you have to give back: Rule 42 & 43 (mixed taxable/exempt supplies), other reversals (block credit list u/s 17(5), e.g. food & beverages).
• (C) Net ITC available = A − B. This is what gets credited to your electronic credit ledger.
• (D) Ineligible ITC — credits you cannot claim at all (e.g. as per section 17(5)).

Section 5 — Values of exempt, nil-rated, and non-GST inward supplies

Purchases that didn't attract any GST — exempt goods (fresh produce, books), nil-rated supplies, non-GST items (petrol). Value only; no tax columns.

Section 5.1 — Interest and late fee for previous tax period

If you're paying interest on delayed payment of tax from a previous month, or late fees from a previous return, declare them here.

Section 6.1 — Payment of tax

The final tally. For each tax type (IGST, CGST, SGST, cess), the portal calculates:

• Tax payable (from your outward supplies)
• Tax paid through ITC (from your electronic credit ledger)
• Tax paid in cash (from your electronic cash ledger — you create a challan PMT-06 if needed)
• Interest and late fee

If credit ledger doesn't have enough, you create a cash challan and pay the difference before filing.

Paying tax — cash ledger vs credit ledger

Two ledgers maintain your tax balances on the GST portal:

• Electronic credit ledger — your accumulated ITC. Used to pay output tax liability. Cannot be used for interest or penalty.
• Electronic cash ledger — money you've deposited via NEFT/RTGS/UPI through challan PMT-06. Can be used for tax, interest, and penalty.

Output tax minus ITC = net cash you have to pay. If ITC exceeds output tax, the excess carries forward to next month (you can't get a refund except in specific cases — exports, inverted duty structure).

Order of utilisation (mandatory)

1. IGST credit first, against IGST liability.
2. Then IGST credit against CGST or SGST liability (your choice).
3. CGST credit against CGST liability, then IGST liability.
4. SGST credit against SGST liability, then IGST liability.
5. CGST and SGST cannot cross-utilise against each other.

8 common mistakes

1. Filing GSTR-1 and GSTR-3B with mismatched figures. The outward supply totals in 3B must equal the GSTR-1 totals. Mismatches generate Form ASMT-10 notices.
2. Claiming ITC not in GSTR-2B. Since 1 Jan 2022, ITC is restricted to what appears in GSTR-2B. Anything else triggers reversal with interest.
3. Forgetting RCM on imports of services. Cloud services from Google, Microsoft, AWS — you pay GST under reverse charge. Many small businesses miss this for years until audit.
4. Skipping nil returns. Even with zero turnover, you still file. Otherwise late fees accumulate.
5. Wrong inter-state allocation. Section 3.2 needs state-wise B2C inter-state sales. Lumping them all together causes reconciliation issues at year-end with GSTR-1.
6. Claiming blocked credits. Food & beverages, club membership, employee insurance, motor vehicles (with exceptions) — ITC on these is explicitly blocked u/s 17(5). Often claimed in error.
7. Not reversing ITC on free samples and gifts. ITC on inputs used to make free samples must be reversed under Rule 42 — easy to miss.
8. Filing without payment. GSTR-3B is "filed" only after tax is paid. If cash ledger is short, the return stays in draft and late fees accrue.

Reconciling with GSTR-1 and GSTR-2B

Two reconciliations matter every month:

GSTR-1 ↔ GSTR-3B

Your outward supplies in GSTR-3B section 3.1(a) must equal the total taxable value plus tax in your GSTR-1 (which you filed earlier — by 11th or 13th of the month). Differences flag in the GST portal's "Comparison of liability" dashboard.

GSTR-2B ↔ Purchase ledger ↔ GSTR-3B section 4(A)(5)

GSTR-2B is auto-generated from what your suppliers reported in their GSTR-1. The ITC you claim in Section 4(A)(5) of GSTR-3B should equal:

• ITC available as per GSTR-2B
• Minus ITC not in your purchase ledger (your supplier reported but you don't have the invoice yet)
• Plus ITC of previous periods you couldn't claim earlier

Late fee & interest

Late fee

• ₹50 per day (₹25 CGST + ₹25 SGST) for normal returns with tax liability.
• ₹20 per day (₹10 + ₹10) for nil returns.
• Capped at ₹5,000 (₹2,500 + ₹2,500) per return.

Interest

• 18% per annum on the unpaid tax amount (not the entire return), calculated from the day after the due date until the date of payment.
• 24% per annum if you claimed and used ITC incorrectly — much higher than regular interest.

Can I correct GSTR-3B after filing?

No. Once filed, GSTR-3B cannot be revised. Errors get corrected in subsequent months — either by increasing/decreasing the relevant section in the next return, or by adjustment in the annual return GSTR-9. Hence the importance of getting it right the first time, which is why software that catches errors at entry pays for itself almost immediately.

Doing this manually is slow. Doing it in software is fast.

Every section above — outward supplies, ITC, reversals, RCM, state-wise breakdown — is computed automatically from your invoice and purchase data inside LekhaBooks. GSTR-2B reconciliation is one button. Section-by-section JSON export ready for the GST portal upload. The free plan supports it. Filing time goes from hours to minutes.