GSTR-1 vs GSTR-3B: Filing Guide & Common Mistakes
TL;DR
- GSTR-1 reports invoice-wise sales detail; GSTR-3B is the summary return through which tax is actually paid.
- Monthly due dates: GSTR-1 on the 11th, GSTR-3B on the 20th. QRMP filers get the 13th and the 22nd/24th, but still pay tax monthly.
- Late fee is Rs 50/day (Rs 20/day for nil returns) plus 18% annual interest on unpaid tax.
- Mismatches between the two returns are one of the most common triggers for a GST scrutiny notice.
GSTR-1 and GSTR-3B are the two returns every regular GST-registered business files, and confusing what each one is for is where most small-business filing mistakes start. One is a detailed sales report with no tax payment attached; the other is where tax is actually declared and paid. Getting the sequencing and reconciliation right between them matters more than most businesses realize until a mismatch notice arrives.
GSTR-1: The Sales Detail Return
GSTR-1 is an invoice-wise statement of outward supplies (sales) for the period, covering B2B invoices, B2C large-value invoices, credit and debit notes, exports, and HSN-wise summaries. It carries no tax payment; it exists purely to feed the buyer's input tax credit and to give the department a granular, invoice-level record of what was sold to whom.
Because your customers' input tax credit depends on what you report here, errors or delays in GSTR-1 directly affect their ability to claim credit, not just your own compliance record; this is a common source of friction with B2B customers when a supplier files late.
GSTR-3B: The Summary Return and Tax Payment
GSTR-3B is a self-declared summary return: total outward supplies, total inward supplies, input tax credit claimed, and net tax payable, all at a consolidated level rather than invoice-wise. This is the return through which GST is actually deposited to the government. Even if turnover is nil for the period, a nil GSTR-3B still needs to be filed to avoid a late fee.
Due Dates: Monthly vs QRMP
| Filing Frequency | GSTR-1 Due Date | GSTR-3B Due Date |
|---|---|---|
| Monthly | 11th of the following month | 20th of the following month |
| QRMP (quarterly) | 13th of the month after quarter-end (IFF optional monthly for the first two months) | 22nd or 24th of the month after quarter-end, depending on state |
QRMP (Quarterly Return Monthly Payment) is available to businesses with aggregate annual turnover up to Rs 5 crore. It reduces filing frequency to once a quarter for both returns, but tax still has to be paid every month using a simplified challan (Form PMT-06), so cash flow planning does not change; only the paperwork frequency does.
GSTR-1 Must Be Filed Before GSTR-3B
The portal generally requires GSTR-1 for a period to be filed before GSTR-3B for that same period can be submitted. Businesses that push GSTR-1 to the last minute often find they have also boxed themselves into a late GSTR-3B, stacking late fees and interest on both returns instead of just one.
Late Fees and Interest
Missing either return attracts a late fee of Rs 50 per day of delay (Rs 20 per day for a nil return), subject to a cap that varies by turnover slab, applied separately to GSTR-1 and GSTR-3B. On top of the late fee, any tax paid after the due date attracts interest at 18% per annum, calculated on the outstanding tax from the due date to the date of actual payment. These add up fast for businesses that fall behind for even a few months, which is why catching up immediately rather than waiting is always the cheaper option.
Why GSTR-1 and GSTR-3B Need to Reconcile
The GST department runs automated reconciliation between the invoice-level sales reported in GSTR-1 and the summary figures declared in GSTR-3B. A recurring or large gap between the two, sales shown in one return but not matched in the other, is one of the most common triggers for a scrutiny notice or a demand for explanation. The same applies to reconciling input tax credit claimed in GSTR-3B against what actually appears in your auto-populated GSTR-2B statement from your suppliers' GSTR-1 filings.
Practical habits that prevent this: finalize your sales register before filing GSTR-1 rather than treating it as a draft, reconcile GSTR-3B figures against GSTR-1 for the same period before submitting, and check GSTR-2B before claiming input tax credit rather than relying on your own purchase register alone.
Common Mistakes to Avoid
- Filing GSTR-3B based on estimated figures and never going back to reconcile against the final GSTR-1
- Claiming input tax credit that does not appear in GSTR-2B, which invites a mismatch query
- Missing the nil-return filing when there is no business activity in a period, thinking no filing is needed
- Amending an invoice in a later GSTR-1 without checking whether the corresponding GSTR-3B period also needs adjustment
- Under QRMP, forgetting the monthly PMT-06 tax payment because the return itself is only due quarterly
If your business is newly registered, see our guide on the GST registration process for what happens before your first return is due, or the composition scheme guide if you are evaluating whether the lighter CMP-08/GSTR-4 filing cycle suits your business better than the regular GSTR-1/3B route.
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Frequently Asked Questions
What is the difference between GSTR-1 and GSTR-3B?
GSTR-1 is a detailed, invoice-wise statement of all outward supplies (sales) made during the period; it has no tax payment attached to it. GSTR-3B is a summary self-declared return of total sales, purchases, input tax credit claimed, and tax paid; it is the return through which GST is actually deposited to the government.
What are the due dates for GSTR-1 and GSTR-3B?
For monthly filers, GSTR-1 is due on the 11th of the following month and GSTR-3B on the 20th. For businesses on the QRMP scheme, GSTR-1 (as IFF or the quarterly form) is due on the 13th of the month after the quarter, and GSTR-3B is due on the 22nd or 24th depending on the state, though tax must still be paid monthly via Form PMT-06.
What is the QRMP scheme and who can opt for it?
QRMP (Quarterly Return Monthly Payment) lets businesses with aggregate annual turnover up to Rs 5 crore file GSTR-1 and GSTR-3B quarterly instead of monthly, while still paying tax every month through a simplified challan. It reduces the filing frequency without deferring the actual cash tax outflow.
What is the late fee for missing GSTR-1 or GSTR-3B?
The standard late fee is Rs 50 per day of delay (Rs 20 per day for nil returns), subject to a cap that varies by return and turnover slab; interest at 18% per annum also applies on any tax paid late. Because the fee runs per return per day, a delay across both GSTR-1 and GSTR-3B compounds quickly.
Why do GSTR-1 and GSTR-3B need to match?
The tax department reconciles the sales reported in GSTR-1 against the sales and tax declared in GSTR-3B, and any mismatch (sales declared in one but not the other, or a large recurring gap) is a common trigger for a scrutiny notice. Consistent, timely reconciliation between the two before filing is the single biggest way to avoid this.
Can GSTR-3B be filed if GSTR-1 has not been filed?
No, GSTR-1 filing for a period generally must be completed before the corresponding GSTR-3B can be filed for that period on the portal. Filing GSTR-1 late therefore also delays GSTR-3B and stacks late fees and interest on both fronts.