This guide is general information. If you would rather a chartered accountant handled it, see GST Return Filing or GST Notice & Appeals.
These two returns are filed by almost every regular GST taxpayer. People often confuse them, but they do different jobs and must agree with each other.
Side-by-side comparison
| GSTR-1 | GSTR-3B | |
|---|---|---|
| What it reports | Details of outward supplies, invoice by invoice | Summary of sales, input tax credit and tax payable |
| Is tax paid with it? | No | Yes |
| Purpose | Gives your buyers their credit data in GSTR-2B | Computes and pays your net liability |
| Monthly due date | 11th of next month | 20th of next month |
Quarterly filers (QRMP)
Small taxpayers under the QRMP scheme file GSTR-1 and GSTR-3B quarterly, around the 13th and the 22nd or 24th of the month after the quarter, depending on state, and pay tax monthly using a challan.
Why matching matters
The department compares the two returns. If sales in GSTR-3B are lower than in GSTR-1, you can get a notice. Credit in GSTR-3B should also not exceed what is shown in your GSTR-2B.
Good practice
- File GSTR-1 first, then prepare GSTR-3B using the same data
- Reconcile purchases with GSTR-2B every month
- Correct errors through amendments in the next return
A simple example of how the two returns connect
Suppose your business sold goods worth ₹10,00,000 plus 18% GST in a month, and bought goods worth ₹6,00,000 plus 18% GST. In GSTR-1, you report each sales invoice, and the tax on them, which is ₹1,80,000. In GSTR-3B, you declare the same ₹1,80,000 as output tax, claim ₹1,08,000 as input credit, if it appears in GSTR-2B and is eligible, and pay the balance of ₹72,000. If GSTR-3B shows less output tax than GSTR-1, the system flags it.
What GSTR-2B is and why it matters
GSTR-2B is a statement generated for you every month, showing the credit available based on what your suppliers reported in their GSTR-1. It is the reference for claiming credit in GSTR-3B. A supplier that files late or not at all means that credit does not appear in your GSTR-2B, and claiming it anyway can lead to a notice.
Correcting mistakes
- Errors in a GSTR-1 already filed can be corrected through amendments in a later return.
- Errors in GSTR-3B are generally corrected in the next month's return.
- Credit claimed wrongly should be reversed with interest as soon as you notice the error.
Practical tips
- File GSTR-1 first and use the same data for GSTR-3B.
- Download GSTR-2B after the due date for suppliers to file and reconcile it with your purchase register.
- Keep a monthly note explaining any difference between books and returns.
Key terms in plain words
- Outward supply: a sale of goods or services by you.
- Input tax credit: GST you paid on business purchases that you can set off against GST you collect.
- Output tax: the GST you collect on your sales.
- Place of supply: the rule that decides whether CGST and SGST or IGST applies.
- ARN: the acknowledgement reference number you get after filing a return.
What an ideal month looks like
Close your sales for the month on the last day, issue any credit notes, and prepare GSTR-1 within the first week. Download GSTR-2B on the 14th, which is after the usual filing date of suppliers, and compare it with your purchase register. Chase suppliers who did not report your invoices. Prepare GSTR-3B before the 18th so you have time to arrange funds for the tax payable. Pay the tax and file by the 20th, and save the acknowledgement and challan.
Signs that something is wrong
- The tax in GSTR-3B is consistently lower than in GSTR-1.
- Your credit claimed is much higher than your GSTR-2B.
- You are paying interest every month because filing slips.
- Your accountant cannot explain the difference between books and returns.
Any one of these is a signal to run a reconciliation and fix the process, not just the month.
When the two returns will not match, and why that is fine
Small differences can be legitimate, for example because of advances received, amendments to earlier invoices or credit notes that fall in different months. What matters is that you can explain each difference with a document. Keep a short reconciliation note each month showing the opening difference, what caused it and when it will be corrected. If a notice arrives, that note becomes the core of your reply.
Questions to ask your accountant each month
- Did GSTR-1 and GSTR-3B match for sales and tax?
- Is any credit claimed that is not in GSTR-2B?
- Are there supplier invoices missing, and have we followed up?
- Did we pay any interest or late fee, and why?
- Is anything due next month that needs funds set aside?
Official source: the GST portal publishes the current due dates, forms and notifications for every return.
Frequently asked questions
Can I file GSTR-3B before GSTR-1?
Technically yes in many cases, but it is better to file GSTR-1 first so your buyers get their credit on time and so your data is consistent.
What if I forget to report an invoice in GSTR-1?
Report it in the next period's GSTR-1, with the correct tax, and pay any interest if the tax was paid late.
Is GSTR-1 needed if there are no sales?
Yes, a nil GSTR-1 is generally required for the period, unless you are covered by a scheme that allows a different filing.
Which return decides the tax I pay?
GSTR-3B. It is where the tax liability and credit are finally computed and paid.
This content is for general information and does not constitute professional advice. Laws, rates and due dates change; confirm the current position for your case. Section references are to the Income-tax Act, 1961 unless stated; the Income-tax Act, 2025 applies to later periods with renumbered sections.