GSTR-1, GSTR-3B and GSTR-9: What They Are, When They Are Due, and How to File Them Yourself
A plain-language guide to India's three most common GST returns for small business owners
MoneyFacts Editorial
Business Software Consultants
Table of Contents
Most small business owners in India know they have to file GST returns. Far fewer understand what each return actually contains, why there are multiple of them, or what happens when they do not match. That confusion is reasonable. The GST return system was not designed for ease of understanding. It was designed for compliance. This article explains the three returns that affect most small and medium businesses in plain terms, walks through what you need to file each one yourself, and is honest about where it makes sense to get help.
Quick Summary (TL;DR)
GSTR-1 reports all your outward sales invoices. GSTR-3B is a monthly summary return where you declare total sales, total purchases, and pay the net GST liability. GSTR-9 is the annual return that reconciles both. Most regular businesses file GSTR-1 monthly or quarterly and GSTR-3B monthly. You can file these yourself using the GST portal. The practical challenges are data accuracy, reconciliation between the two returns, and not missing due dates. Accounting software reduces all three by building return data from your transaction records as you work.
Why there are multiple GST returns
The GST system is built on a matching principle. When you raise a sales invoice and report it in GSTR-1, your customer sees it in their purchase register on the GST portal. When they claim input tax credit on that purchase, the government cross-references it against what you reported. The system is designed so that credits can only flow through from properly reported invoices.
GSTR-3B is a separate monthly payment mechanism. You declare your total tax liability and total eligible input tax credit, compute the net amount owed, and pay it. GSTR-1 provides the invoice-level detail. GSTR-3B handles the settlement. They serve different purposes, which is why they are filed separately.
GSTR-9 is the annual reconciliation. At the end of the financial year, it pulls together everything you reported across all monthly returns and gives the government a consolidated picture of your annual GST position.
The core rule: GSTR-1 is what you sold. GSTR-3B is what you owe. GSTR-9 is the annual summary of both. When these three do not agree with each other and with your books, that is when notices happen.
GSTR-1: Your outward sales register
GSTR-1 is a detailed statement of every invoice you raised in a given period. It includes B2B invoices (sales to other registered businesses), B2C invoices (sales to consumers or unregistered buyers), credit notes, debit notes, and export invoices if applicable.
| What it covers | Who files it | Due date |
|---|---|---|
| All outward sales invoices, credit notes, debit notes | All regular GST-registered businesses | 11th of the following month (monthly filers) |
| B2B, B2C, exports, nil-rated and exempt supplies | Quarterly filers under QRMP scheme | 13th of the month following the quarter |
The QRMP scheme (Quarterly Return Monthly Payment) allows businesses with annual turnover up to Rs. 5 crore to file GSTR-1 quarterly while still making monthly tax payments. If you are eligible and your transaction volume is manageable, this reduces the filing frequency from 12 to 4 times per year for GSTR-1.
B2B invoices (to registered buyers) must be reported individually, invoice by invoice, because the buyer’s input tax credit depends on your accurate reporting. B2C invoices above Rs. 2.5 lakh must also be reported individually. B2C invoices below this threshold can be reported as a consolidated state-wise summary. This distinction matters for understanding how much detail your records need to contain.
GSTR-3B: Your monthly tax payment return
GSTR-3B is filed every month by most regular taxpayers. Unlike GSTR-1, it is a summary return, not an invoice-level report. You declare your total outward taxable supplies, your total eligible input tax credit, and compute the net tax liability for the month. The tax due is paid at the time of filing.
| What it covers | Who files it | Due date |
|---|---|---|
| Total sales, total ITC claimed, net GST liability and payment | All regular GST-registered businesses | 20th of the following month |
| Monthly tax payment for quarterly GSTR-1 filers | QRMP scheme taxpayers | 25th of the following month (via PMT-06 challan) |
The most important discipline with GSTR-3B is accuracy. Because it is a summary return, errors are less visible than in GSTR-1 but their consequences are more direct. Understating liability means underpayment and interest. Overstating ITC means claiming credits you are not entitled to, which triggers scrutiny. The numbers in GSTR-3B must reconcile with GSTR-1, which means they must reconcile with your actual books.
A textile trader in Surat had been filing both returns on time for two years without any issues. In the third year, an employee started entering certain purchases in the accounts a month later than the actual receipt date. The stock came in, the goods were sold, but the purchase entries lagged. When the annual GSTR-9 reconciliation happened, the ITC claimed in GSTR-3B for several months did not match the purchase invoices reported by suppliers in their GSTR-1 filings. The government portal flagged a mismatch. The trader had not done anything fraudulent. The entries were all eventually traceable. But reconstructing the timeline and responding to the notice took the CA almost three weeks of additional work. The return itself was accurate in aggregate. The timing mismatch in the underlying entries was enough to trigger the process.
GSTR-9: The annual return
GSTR-9 is filed once per year, covering the full financial year from April to March. It consolidates the data from all your GSTR-1 and GSTR-3B filings for the year, compares them, and requires you to account for any differences. It also captures details about input tax credit, amendments made during the year, and HSN-wise summary of supplies.
| What it covers | Who files it | Due date |
|---|---|---|
| Annual reconciliation of all outward and inward supplies, ITC, and tax paid | Regular taxpayers with turnover above Rs. 2 crore | 31st December of the following financial year |
| GSTR-9C (reconciliation statement, CA-certified) | Businesses with turnover above Rs. 5 crore | Filed alongside GSTR-9 |
Businesses with aggregate annual turnover up to Rs. 2 crore are currently exempt from filing GSTR-9, though they may still file voluntarily. Verify the current exemption threshold on the GST portal, as this has been revised in previous years and may change again.
Can you file GST returns yourself?
Yes. The GST portal at gstin.gov.in is accessible to any registered taxpayer and designed to accept self-filed returns. Many small business owners file their own returns, particularly for GSTR-1 and GSTR-3B. It is not complicated if your records are in order. Here is what the process looks like.
Compile all sales invoices for the month. For B2B invoices, you need the buyer’s GSTIN, invoice number, date, taxable value, and tax amounts. For B2C invoices above Rs. 2.5 lakh, the same detail is required individually. Below that threshold, a state-wise total is sufficient. If you use billing software, this data is already structured and can be exported directly to the portal format.
Log in to the GST portal using your GSTIN and credentials. Navigate to Returns, then GSTR-1 for the relevant period. You can enter invoices manually using the portal’s forms, or upload a JSON or Excel file if you have the data prepared in the correct format. Once all invoices are entered, review the summary and submit. GSTR-1 must be filed before GSTR-3B for the same period.
From your accounts, calculate total outward taxable supplies by rate (5%, 12%, 18%, 28%), total exempt or nil-rated supplies, and total eligible input tax credit from your purchase invoices for the month. Cross-check: the taxable supply total in GSTR-3B should match the total reported in your GSTR-1 for the same period. If they do not, find the difference before filing.
Enter the summary figures on the GSTR-3B form. The portal calculates the net tax liability after applying available ITC. Pay the balance through net banking, UPI, or the electronic cash ledger. Once payment is confirmed, submit and file the return. Keep the acknowledgement number.
Before filing either return each month, compare your figures against your purchase register and your supplier’s reported invoices in GSTR-2B (available on the portal). ITC claimed in GSTR-3B should only cover invoices that appear in GSTR-2B. Claiming ITC on invoices your supplier has not yet reported is a common source of mismatches and notices.
Things to be mindful of when filing yourself
Self-filing is practical and entirely achievable. These are the areas where errors most commonly occur.
- File GSTR-1 before GSTR-3B. The portal requires this sequence. Filing out of order causes errors.
- Match your GSTR-3B sales figures to your GSTR-1. A difference between the two returns is a reconciliation item the government will eventually flag.
- Only claim ITC on invoices that appear in GSTR-2B. Do not claim credits on purchase invoices your supplier has not yet uploaded.
- Do not miss due dates. Late filing attracts a late fee of Rs. 50 per day (Rs. 20 for nil returns), and interest at 18 percent per annum on unpaid tax.
- Keep records of all filed returns and payment challans. The acknowledgement number and tax payment reference are your evidence of compliance.
- Amend errors promptly. Mistakes in GSTR-1 can be corrected in the following month’s return. Do not leave known errors uncorrected.
- For GSTR-9, do not wait until December. The annual return requires reconciling twelve months of data. Starting the reconciliation in October gives you time to identify and correct discrepancies before the deadline.
Self-filing works well when your transactions are straightforward and your records are current. Consider involving a CA if you have received a notice, if your GSTR-2B reconciliation shows significant mismatches, if you operate across multiple states or have complex supply chains, or if you are approaching the GSTR-9C threshold where a certified reconciliation statement is required. The cost of professional review at these points is almost always less than the cost of resolving a compliance issue that compounds over time.
How accounting software changes the filing process
The most time-consuming part of self-filing is not navigating the GST portal. It is preparing accurate data before you get there. Every invoice needs to be accounted for. Every purchase needs to be recorded with the correct GSTIN and tax detail. The GSTR-3B figures need to reconcile with GSTR-1. And all of this needs to happen monthly, every month, without gaps.
When your billing and accounting happen in dedicated software, the return data is a byproduct of your daily operations rather than a separate preparation exercise.
Filing without accounting software
- Compile invoices from email, Word, or Excel at month end.
- Manually calculate CGST/SGST/IGST totals by rate.
- Cross-check purchase register against GSTR-2B manually.
- Enter data on the portal or prepare upload files by hand.
- Risk of data entry errors at each step.
- GSTR-9 reconciliation requires reconstructing 12 months of data.
Filing with integrated accounting software
- Every invoice raised auto-populates GSTR-1 data.
- Tax splits calculated automatically at the point of billing.
- Purchase entries feed the ITC register in real time.
- GSTR-1 and GSTR-3B data available as a review, not a calculation.
- Mismatches between returns flagged before filing, not after.
- GSTR-9 reconciliation uses the same records already in the system.
MoneyFacts records every sale and purchase with the correct GSTIN, HSN code, and tax classification. The GSTR-1 outward supply data is built automatically from your invoices. Your ITC register is maintained from your purchase entries. When it is time to file, the preparation is a review of what the system has already compiled rather than a monthly reconstruction exercise. For businesses managing more than a few dozen transactions per month, this difference in effort is significant.
If you have ten invoices a month and one purchase supplier, manual filing is entirely manageable. If you have 50 or more invoices across multiple GST rates, multiple suppliers, and a growing purchase register, software is not a convenience. It is what makes consistent, accurate monthly compliance achievable without a significant chunk of someone’s working time devoted to it.
Frequently Asked Questions
What happens if I miss a GST return due date?
Late filing attracts a late fee: Rs. 50 per day for returns with tax liability, Rs. 20 per day for nil returns, subject to a maximum cap that varies by return type. In addition, interest at 18 percent per annum applies to any unpaid tax from the due date. Missing GSTR-1 also blocks your customers from seeing your invoices in their GSTR-2B, which can affect their ability to claim input tax credit and damage those business relationships.
Can I correct an error in a filed GST return?
Errors in GSTR-1 can generally be corrected in the following month’s return by filing an amendment. GSTR-3B corrections are handled through adjustments in subsequent months. The GST portal does not allow direct editing of filed returns. For significant errors, especially those affecting tax liability, consult a CA before amending to ensure the correction is handled in the right sequence.
What is GSTR-2B and why does it matter?
GSTR-2B is an auto-generated statement available on the GST portal showing all purchase invoices that your suppliers have reported in their GSTR-1 filings. It is the basis for your input tax credit eligibility. ITC claimed in GSTR-3B should be limited to invoices appearing in GSTR-2B for that period. Claiming ITC on invoices not yet reflected in GSTR-2B is a common compliance risk.
Do I need a CA to file GST returns?
No. Any GST-registered taxpayer can self-file using the government portal. A CA is not legally required for GSTR-1 or GSTR-3B filing. GSTR-9C, the reconciliation statement required for businesses above Rs. 5 crore turnover, must be certified by a CA or cost accountant. For straightforward businesses with current records and moderate transaction volumes, self-filing is practical. For complex supply chains, multi-state operations, or businesses that have received notices, professional support is advisable.
Let your accounting software do the GST groundwork
MoneyFacts builds your GSTR-1 and GSTR-3B data from every invoice and purchase entry you record. No end-of-month reconstruction. No manual calculation of tax splits. When it is time to file, the data is already there. Billing, inventory, accounts and GST compliance in one platform built for Indian SMEs.
See MoneyFacts in action
