GSTR-1 vs GSTR-3B is the comparison every GST-registered business has to get right. The two returns are linked, and a mismatch between them is one of the most common reasons for GST notices. Here is what each return does and how to file them correctly in 2026.
Key takeaways
- GSTR-1 reports invoice-level sales; GSTR-3B is where you pay tax and claim ITC.
- GSTR-1 now auto-fills GSTR-3B, so the sales return has to be right first.
- Monthly GSTR-1 is due on the 11th; GSTR-3B on the 20th.
- Mismatches trigger DRC-01B (liability) and DRC-01C (ITC) notices.
What is GSTR-1?
GSTR-1 is a statement of outward supplies. It reports invoice-level details of B2B sales, summary details of B2C sales, credit and debit notes, exports and advances. The data you upload flows into your buyers’ GSTR-2B, which decides how much input tax credit they can claim.
What is GSTR-3B?
GSTR-3B is a summary return. It is where you declare total sales, claim input tax credit and pay the net tax. Interest and late fees are computed on it.
Key differences
| Point | GSTR-1 | GSTR-3B |
|---|---|---|
| Nature | Invoice-wise statement of sales | Summary return with tax payment |
| Tax payment | No | Yes |
| ITC claim | No | Yes |
| Effect on buyers | Populates buyers’ GSTR-2B | No direct effect |
| Monthly due date | 11th of next month | 20th of next month |
| QRMP due date | 13th of month after quarter | 22nd or 24th of month after quarter, by state |
How the two returns now work together
- Auto-population: sales declared in GSTR-1 are auto-filled into GSTR-3B.
- GSTR-1A: if you missed or misreported an invoice in GSTR-1, you can correct it in GSTR-1A before filing GSTR-3B for the same period.
- Hard-locking: the auto-filled liability in GSTR-3B can no longer be edited, so GSTR-1 must be right.
- Invoice Management System (IMS): buyers accept, reject or keep pending each supplier invoice, and only accepted invoices flow into their GSTR-2B.
Common mistakes and how to avoid them
- Claiming ITC not in GSTR-2B. Excess claims trigger DRC-01C notices — see how to reply to a GST notice.
- Sales in GSTR-1 higher than in GSTR-3B. This triggers DRC-01B notices. Reconcile every month.
- Wrong place of supply. Charging CGST + SGST instead of IGST, or the reverse, means paying tax again under the correct head.
- Ignoring nil returns. Nil returns must still be filed, or late fees accumulate — nil GST return filing covers quiet months.
- Old pending returns. Returns cannot be filed after three years from the due date, so clear backlogs quickly.
Late fees and interest
Late fee: ₹50 per day (₹20 for nil returns), capped based on turnover. Interest: 18% per annum on tax paid late, calculated on the cash portion.
Filing360 handles this on monthly GST return filing with WhatsApp reminders before each due date.
A monthly close that actually works
Lock sales invoices by the 8th so GSTR-1 can go on the 11th. Reconcile GSTR-2B by the 16th before you claim ITC in GSTR-3B on the 20th. That calendar leaves room for GSTR-1A corrections and for finance to query a supplier whose invoice is missing from 2B. Filing 3B first and “fixing 1 later” is how DRC-01B lands.
QRMP, in plain language
If turnover is up to ₹5 crore you can file GSTR-1 and GSTR-3B quarterly, with monthly tax payment in some months. The due dates shift to the 13th (GSTR-1) and the 22nd or 24th (GSTR-3B) after the quarter, depending on state. QRMP does not mean you can skip invoice hygiene — IMS and 2B still run every month for your buyers.
What to do this week
- Download last month’s GSTR-1, GSTR-3B and GSTR-2B and tick every mismatch.
- Turn on invoice numbering that never repeats, including credit notes.
- Put the 11th and 20th (or your QRMP dates) on a shared calendar with a two-day buffer.
Worked scenario
A trader uploads ₹50 lakh of B2B invoices in GSTR-1 and then types ₹47 lakh into GSTR-3B because a credit note was missed. Auto-population should have prevented the edit; if an older period still shows a gap, DRC-01B follows. The fix is GSTR-1A (current period) or the next return — not a silent journal in the books. The same trader claiming ₹2 lakh extra ITC versus GSTR-2B is a DRC-01C. Both notices are cheaper to prevent with a close than to answer with a GST notice reply.
Related reading: GSTR-9 due date for FY 2025-26 and GST composition scheme.
If you want the 11th and 20th off your plate, Filing360 reconciles books to GSTR-1 and GSTR-2B, files both returns, and pings you on WhatsApp before each due date. That is the practical way to keep GSTR-1 vs GSTR-3B from becoming a notice. See GST return filing. Keep a one-page monthly recon even if a CA files — you will need it when a notice or the GSTR-9 due date arrives.
Frequently asked questions
Can I file GSTR-3B before GSTR-1?
The portal allows it, but since GSTR-3B now auto-fills from GSTR-1, filing GSTR-1 first is the correct practice.
Can I revise GSTR-3B?
No. Corrections are made in the next period’s return or through GSTR-1A for sales.
Are both returns required for composition dealers?
No. Composition dealers file CMP-08 quarterly and GSTR-4 annually.
What is IMS in GST?
Invoice Management System lets buyers accept, reject or keep pending supplier invoices. Only accepted invoices flow into GSTR-2B, which is why GSTR-1 accuracy now affects your customers’ credit as well as your own 3B.
Tired of tracking due dates? Start GST return filing with Filing360.
