A GST filing checklist for small businesses is a short, repeatable list of checks you run every month before you file GSTR-1 and GSTR-3B. Following it helps you file on time, claim only the input tax credit (ITC) you are entitled to, and avoid late fees and interest. This guide gives you a month-start to month-end routine you can adopt today.
1. Know which returns you file and when
Your return schedule depends on your registration type and turnover. Start the month by confirming where you stand.
- Regular monthly filers file GSTR-1 (outward supplies) and GSTR-3B (summary return and tax payment) every month.
- QRMP scheme taxpayers file returns quarterly but pay tax monthly. See our QRMP GSTR-3B checklist for how that cycle works.
- Composition taxpayers follow a different, simpler cycle and do not claim ITC.
- Special registrations such as GST TDS deductors and e-commerce operators file separate returns (GSTR-7 and GSTR-8).
The usual due dates are fixed by law, but extensions are sometimes notified. The GSTR-1 date is usually the 11th and the GSTR-3B date usually the 20th of the following month for monthly filers. Always check the GST portal for the current date and any extension before you plan around it.
2. Get your sales records in order first
Your GSTR-1 is only as good as your sales register. Before you file, check that:
- every invoice, credit note and debit note of the month is recorded, with no gaps in the invoice numbers;
- each invoice carries the mandatory fields. Our Rule 46 invoice checklist lists them;
- you have used the right document: tax invoice, bill of supply or delivery challan, as explained in this comparison;
- customer GSTINs, place of supply, HSN/SAC codes and tax rates are correct line by line;
- if e-invoicing applies to you, every B2B invoice has its IRN. Read who must generate an IRN if you are unsure.
Also check advances received, exports and any sales that are exempt, nil-rated or non-GST, because these are reported in separate sections.
3. Reconcile your purchases with GSTR-2B
GSTR-2B is the auto-drafted ITC statement generated from what your suppliers have filed. It is the base for your ITC claim, so compare it with your purchase register every month.
- Match invoice by invoice: supplier GSTIN, invoice number, date, taxable value and tax amount.
- List invoices that appear in your books but not in GSTR-2B. Follow these up with the supplier; claim the credit only once it appears or you are sure it is eligible.
- List invoices that appear in GSTR-2B but not in your books. Check whether the purchase is genuine and whether you actually received the goods or services.
- Check for credit you cannot take. See blocked credit under Section 17(5).
- Check whether any supplier invoice has stayed unpaid for a long time. The 180-day rule under Rule 37 may require you to reverse ITC.
Keep a note of the open items so they carry forward to next month instead of being forgotten.
4. Handle reverse charge, credit notes and special items
Some entries are easy to miss because no regular supplier invoice triggers them.
- Reverse charge (RCM): if you buy something on which you must pay tax yourself, you report and pay it in GSTR-3B. Our guide on the reverse charge mechanism covers the accounting and the ITC claim.
- Credit notes: there are time limits for issuing them and adjusting tax. See GST credit notes under Section 34.
- Rule 86B: if your monthly taxable supplies are large, a part of the tax may need to be paid in cash. Check Rule 86B to see if it applies to you.
5. File GSTR-1, then reconcile it with GSTR-3B
File GSTR-1 first, because it feeds your outward tax liability. Before filing, preview the summary and compare the totals with your sales register. After GSTR-1 is filed, prepare GSTR-3B.
Many notices arise from mismatches between the two returns. Use our GSTR-1 vs GSTR-3B reconciliation checklist to find differences in taxable value and tax before you submit. Fixing a small difference this month is far easier than explaining it later.
6. Pay the tax and file GSTR-3B
In GSTR-3B you offset your liability using the available ITC and pay the balance in cash. A sensible order of work:
- Confirm the tax liability on outward supplies and RCM.
- Confirm the ITC you are claiming, and any reversals.
- Check your electronic cash and credit ledgers for the balance.
- Create the challan early if cash is short, so the payment reflects before you file.
- Submit and file the return. Keep the acknowledgement.
If you do file late, a late fee and interest apply. Our late fee and interest worked example shows how they are calculated, so you can see what a delay would really cost.
7. Close the month with a record
After filing, spend a few minutes on housekeeping:
- save the filed returns and challans in a folder for the month;
- post the tax payment and ITC entries in your books so the GST ledgers agree with the portal;
- note the open reconciliation items and the next due dates;
- check the next month in your compliance calendar, because GST sits alongside TDS and PF/ESI dates.
Key takeaways
- Confirm your return type and current due dates on the GST portal every month.
- Clean sales records and correct invoice details make GSTR-1 straightforward.
- Reconcile purchases with GSTR-2B before claiming ITC.
- Do not forget RCM, credit notes and any reversals.
- Reconcile GSTR-1 with GSTR-3B, then pay and file early.
- Keep a monthly file of returns, challans and open items.
If your books, invoices and GST data sit in one place, this routine becomes much faster. Smart Books is Aicountly's accounting software for Indian businesses. For specific questions about your own situation, please confirm with your chartered accountant.
