Every regular GST-registered business files two main returns: GSTR-1 (the detail of your sales) and GSTR-3B (a summary where you actually pay the tax). If GSTR-1 is the list, GSTR-3B is the settlement. This guide keeps it simple.
New to GSTR-1? Read our companion guide on how to file GSTR-1 first — the two work together.
What Is GSTR-3B?
GSTR-3B is a self-declared summary of a tax period: your total outward sales, the tax on them, the input tax credit you are claiming on purchases, and the net tax you pay after adjusting the two. You do not list every invoice here — just the totals.
When Is It Due?
- Monthly filers — by the 20th of the next month
- QRMP filers (turnover up to ₹5 crore, filing quarterly) — by the 22nd or 24th of the month after the quarter, depending on your state
Late filing attracts a late fee of ₹50 per day (₹20 for nil returns), capped per return at ₹2,000 for turnover up to ₹1.5 crore, ₹5,000 for ₹1.5–5 crore and ₹10,000 above that (₹500 for nil returns), plus 18% annual interest on tax paid late. The date matters.
The Tables That Matter
| Table | What goes in it |
|---|---|
| 3.1 | Outward supplies — your taxable sales and the tax on them |
| 3.2 | Inter-state sales to unregistered persons (a breakup of 3.1) |
| 4 | Eligible Input Tax Credit from your purchases |
| 5 | Exempt, nil-rated and non-GST inward supplies |
| 6.1 | Payment of tax — net cash you pay after credit |
Your GSTR-3B outward tax should match the GSTR-1 you filed for the same period; mismatches are a common reason for GST notices. Since the July 2025 tax period, the sales-tax figures auto-filled into GSTR-3B from GSTR-1 can no longer be edited in GSTR-3B. Correct a mistake through GSTR-1A before you file 3B. Software that produces both from the same sales data keeps them in sync.
Common Mistakes to Avoid
- Claiming more input credit than your suppliers have actually reported (check GSTR-2B first)
- Forgetting to reverse credit on exempt sales
- Filing 3B without reconciling it to 1 — a common trigger for notices
- Missing the due date on a nil month (a nil return is still mandatory)
How Billing Software Prepares It
You should never build GSTR-3B by hand from a register. Billux adds up your outward supplies and tax automatically and gives you a GSTR-3B summary that maps to the portal tables — so you review the numbers and enter them, rather than calculating them. It also exports GSTR-1 and reconciles GSTR-2B, keeping the three consistent.
Before you file, make sure your items carry the right rates. Check the new GST rates list, and see how credit notes reduce your output tax.
The Bottom Line
GSTR-3B is a summary, not a mystery. Know the tables, respect the date, and let your billing data do the arithmetic.
Get GST-ready billing free at billux.in/register.
Frequently Asked Questions
What is the due date for GSTR-3B?
Monthly filers must file by the 20th of the following month. Quarterly filers in the QRMP scheme file by the 22nd or 24th of the month after the quarter, depending on their state.
What is the late fee for GSTR-3B?
₹50 a day (₹20 for a nil return), capped per return at ₹2,000 for turnover up to ₹1.5 crore, ₹5,000 for ₹1.5–5 crore and ₹10,000 above ₹5 crore (₹500 for nil). Interest at 18% a year is charged on tax paid late.
Can I change auto-filled values in GSTR-3B?
Not the tax liability auto-filled from GSTR-1. Since the July 2025 tax period it is locked in GSTR-3B. Correct it by filing GSTR-1A for the same period before you file GSTR-3B. Input tax credit figures can still be adjusted.
What is the difference between GSTR-1 and GSTR-3B?
GSTR-1 lists your sales invoice by invoice. GSTR-3B is the summary where you declare total tax, claim input credit and actually pay. The sales figures in both should match for the same period.
Do I need to file GSTR-3B if there were no sales?
Yes. A nil GSTR-3B must still be filed for every period, or late fees apply. A nil return can usually be filed quickly, including by SMS on the GST portal.
