If you are registered under GST, two returns come up every month: GSTR-1 and GSTR-3B. Many new business owners mix them up, or assume one of them is enough. They are not the same, and one cannot replace the other. This guide explains each return in plain words, with due dates, the filing order, and what happens when the two do not agree.
Quick answer: GSTR-1 is the invoice-level statement of what you sold in a period, while GSTR-3B is the summary return where you declare your net GST, claim input tax credit and pay the tax. Both are compulsory for regular taxpayers, both must agree, and the order matters: file GSTR-1 first, then GSTR-3B.
What is GSTR-1?
GSTR-1 is your statement of outward supplies, filed under Section 37 of the CGST Act, 2017. It lists what you sold, invoice by invoice: sales to registered businesses (B2B), sales to consumers, exports, SEZ supplies, debit notes, credit notes and amendments to earlier invoices. It also carries an HSN-wise summary of outward supplies.
Two facts about GSTR-1 surprise most first-time filers. First, no tax is paid through GSTR-1. It is a disclosure, not a payment. Second, your GSTR-1 data feeds your buyers’ GSTR-2B statement, which they use to claim their input tax credit. A missing or wrong invoice in your GSTR-1 can therefore block your customer’s credit, even though your own tax payment is unaffected at that stage.
What is GSTR-3B?
GSTR-3B is your summary self-assessment return, filed under Section 39 of the CGST Act, 2017. Here you declare your total outward supplies by tax rate, claim eligible input tax credit (ITC), report any reverse-charge liability, and pay the net tax due. This is the return where tax is actually paid, through the electronic cash ledger and electronic credit ledger.
Unlike GSTR-1, GSTR-3B works in totals only. It does not ask for invoice numbers. It asks: how much tax do you owe on your sales, how much credit can you set off, and what balance remains to be paid?
GSTR-1 vs GSTR-3B: the full comparison
| Point | GSTR-1 | GSTR-3B |
|---|---|---|
| Purpose | Reports outward supplies in detail | Summarises tax liability, ITC claimed and tax paid |
| Level of detail | Invoice by invoice | Consolidated totals only |
| Tax payment | No tax is paid | Net GST is paid here |
| Legal section | Section 37, CGST Act 2017 | Section 39, CGST Act 2017 |
| Effect on others | Feeds buyers’ GSTR-2B | Your own ITC depends on suppliers’ GSTR-1 via your GSTR-2B |
| Filing order | Filed first | Filed after GSTR-1 |
| Can it be revised? | Not directly; corrections go through GSTR-1A before GSTR-3B for the same period, or a later period’s GSTR-1 | No; once filed it cannot be revised, and errors are adjusted in a later period’s return |
Due dates: monthly filers
For monthly filers, the dates are fixed and the gap between them is deliberate:
| Return | Due date |
|---|---|
| GSTR-1 | 11th of the following month |
| GSTR-3B | 20th of the following month |
So for October sales, GSTR-1 is due by 11 November and GSTR-3B by 20 November. The nine-day gap exists so your sales data can flow into the system before you finalise your tax payment.
Due dates: QRMP filers
Taxpayers with aggregate annual turnover up to Rs 5 crore in the preceding financial year can opt for the Quarterly Return Monthly Payment (QRMP) scheme, as per the GST portal. Under QRMP:
| Return | Due date |
|---|---|
| GSTR-1 | 13th of the month after the quarter ends |
| GSTR-3B | 22nd or 24th of the month after the quarter ends, depending on your state group |
| Monthly tax payment | PMT-06 challan by the 25th of each of the first two months of the quarter; the third month’s tax is paid with the quarterly GSTR-3B |
QRMP filers can also use the Invoice Furnishing Facility (IFF) to upload B2B invoices monthly, so their buyers do not have to wait a full quarter for credit.
How the two returns work together
The filing order is not a suggestion. It is how the system is built:
- File GSTR-1 first. Your sales data is recorded invoice by invoice.
- GSTR-3B picks up your outward tax from GSTR-1. Since the July 2025 tax period, the main outward-liability values in GSTR-3B are auto-populated from GSTR-1, GSTR-1A and IFF, and cannot be edited downwards in GSTR-3B itself, according to GSTN guidance reported in 2026 filing guides. If a figure is wrong, correct it through GSTR-1A before filing GSTR-3B for the same period.
- Your buyers get their GSTR-2B from your GSTR-1. Late or missing GSTR-1 filing delays their credit.
- Your ITC in GSTR-3B comes from your GSTR-2B, which is built from your suppliers’ GSTR-1 filings. If a supplier has not filed, that invoice will not appear in your GSTR-2B, and claiming it anyway is what triggers a mismatch notice. Our separate guide on input tax credit and blocked credits explains which credits are eligible and which are blocked.
There is also a reverse lock: GSTR-1 for a period cannot be filed if the previous period’s GSTR-3B is still pending, under Rule 59(6) of the CGST Rules. A missed GSTR-3B therefore blocks the next month’s GSTR-1 as well, and the chain effect spreads to your buyers.
What happens if GSTR-1 and GSTR-3B do not match?
The GST system compares the two returns automatically. Two different intimations cover the two directions of mismatch:
- DRC-01B (Rule 88C): issued when the tax on outward supplies declared in GSTR-1 (or IFF) is higher than the tax declared and paid in GSTR-3B, beyond the prescribed limit. In plain terms, you have shown more sales than you paid tax on.
- DRC-01C (Rule 88D): issued when the ITC claimed in GSTR-3B exceeds the ITC available in your GSTR-2B beyond the prescribed limit. In plain terms, you have claimed more credit than your suppliers’ filings support.
On receiving either intimation, reply on the GST portal: either pay the shortfall with interest, or explain the difference with documents and a reconciliation. Ignoring an intimation is the worst option, because it can lead to recovery proceedings and to blocking of later filings. If you have already missed a GSTR-3B deadline, read our guide on the GSTR-3B missed deadline, late fee and how to file now.
Late fee and interest
Delay costs money on both returns, and the two charges work differently:
- Late fee: Rs 50 per day (Rs 25 CGST + Rs 25 SGST) for a return with tax liability, and Rs 20 per day for a nil return, under Section 47 of the CGST Act. From the July 2025 return period, the late-fee cap is a uniform Rs 10,000 per return, while nil returns stay capped at Rs 500. Late fee must be paid in cash, not from input tax credit.
- Interest: 18% per annum on tax paid late, under Section 50 of the CGST Act. Interest is charged on the tax amount only, and it is not capped like the late fee.
Note the difference: late fee punishes late filing, interest punishes late payment. A return filed on time but with tax paid late still draws interest.
Worked example: a small shop
Take a shop that sells goods worth Rs 5,00,000 in a month, all taxed at 18%.
Step 1 — GSTR-1. The shop uploads every sales invoice by the 11th of the next month. Output tax shown: Rs 5,00,000 × 18% = Rs 90,000. No payment is made at this stage.
Step 2 — Check GSTR-2B. From its purchases, the shop has eligible ITC of Rs 40,000, visible in its GSTR-2B.
Step 3 — GSTR-3B. The outward tax of Rs 90,000 is auto-populated from GSTR-1. The shop claims Rs 40,000 ITC. Net tax payable: Rs 90,000 − Rs 40,000 = Rs 50,000. It files GSTR-3B by the 20th and pays Rs 50,000.
If the shop had missed one invoice in GSTR-1, the auto-populated outward tax in GSTR-3B would be lower than the real liability, and the system would raise a DRC-01B intimation for the shortfall. If it had claimed Rs 60,000 ITC without GSTR-2B support, a DRC-01C intimation would follow instead.
Practical monthly checklist
- Collect every sales invoice for the month, including credit and debit notes.
- File GSTR-1 by the 11th (13th after the quarter for QRMP filers).
- Review the auto-populated outward tax in GSTR-3B against your own sales register.
- Reconcile your purchase register with GSTR-2B before claiming ITC.
- File GSTR-3B by the 20th (22nd or 24th for QRMP filers) and pay the net tax.
- Save copies of both filed returns and the payment challan.
- Watch for DRC-01B or DRC-01C intimations after filing, and reply promptly with payment or an explanation.
Common mistakes to avoid
- Uploading only some invoices in GSTR-1. The missing sales show up as a GSTR-1 vs GSTR-3B gap sooner or later.
- Claiming ITC that is not yet in GSTR-2B. Wait for the supplier’s filing; an early claim invites a DRC-01C intimation.
- Trying to lower outward tax inside GSTR-3B. Since July 2025 the field is auto-populated and locked; correct the source through GSTR-1A instead.
- Filing GSTR-3B without GSTR-1. The portal blocks GSTR-3B for the period until GSTR-1 is filed.
- Skipping a nil return. Even with no sales, a regular taxpayer must file; a nil GSTR-3B filed late still draws Rs 20 per day.
- Forgetting the annual return. Monthly and quarterly filings do not replace the annual return; see our GSTR-9 annual return guide for its due date and late fee.
Frequently asked questions
What is the difference between GSTR-1 and GSTR-3B?
GSTR-1 is a detailed, invoice-level list of all sales you made in the tax period. GSTR-3B is a summary where you work out your net GST payable, claim input tax credit and actually pay the tax. GSTR-1 is about disclosure; GSTR-3B is about payment.
Which return is filed first, GSTR-1 or GSTR-3B?
GSTR-1 is filed first. The due dates reflect this: the 11th for GSTR-1 and the 20th for GSTR-3B for monthly filers. GSTR-3B’s outward tax figures are drawn from GSTR-1, so filing in the right order avoids a mismatch from the start.
Can GSTR-3B be filed without filing GSTR-1?
No. For the same tax period, the portal does not allow GSTR-3B filing until GSTR-1 has been filed, because the outward liability in GSTR-3B is auto-populated from GSTR-1. File GSTR-1 first, then GSTR-3B.
What happens if GSTR-1 and GSTR-3B do not match?
The system issues an intimation: DRC-01B under Rule 88C when GSTR-1 shows more outward tax than GSTR-3B paid, or DRC-01C under Rule 88D when ITC claimed in GSTR-3B exceeds GSTR-2B. You must then pay any shortfall with 18% interest, or explain the difference on the portal with supporting documents.
Can GSTR-3B be revised after filing?
No. Once GSTR-3B is filed, it cannot be revised. Errors are corrected in a later period’s return: a missed sale is reported through a later GSTR-1 and the tax difference is settled in the next GSTR-3B, and excess ITC claimed is reversed in a later period.
Is a nil GSTR-3B return compulsory, and what is the late fee?
Yes. A regular taxpayer must file GSTR-3B even in a month with no transactions, as a nil return. A nil return filed late draws a late fee of Rs 20 per day, capped at Rs 500.
Official sources
- GST portal — returns, due dates and filing: https://www.gst.gov.in/
- Central Board of Indirect Taxes and Customs (CBIC) — GST law and notifications: https://cbic.gov.in/
Reviewed by Asuthod Rathod, CA. Last updated: 3 November 2026.
Disclaimer: This article explains GST returns in simple terms for general information. Tax rules and portal features change from time to time. Check the GST portal or consult a qualified tax professional before filing.
Editorial byline for eircicai GST guides — covering registration, return filing, rates, and compliance for small businesses. Content is reviewed by Asuthod Rathod, CA.