GSTR-1 is the invoice-level statement of outward supplies, while GSTR-3B is the summary return through which a taxpayer actually pays GST. GSTR-1 carries no tax payment; GSTR-3B reports net liability and input tax credit and discharges the tax. Data filed in GSTR-1 now auto-populates GSTR-3B.
What each return is
GSTR-1 is a statement of outward supplies filed under Section 37 of the CGST Act. It captures every B2B invoice, consolidated B2C supplies, credit and debit notes, exports and amendments. No tax is paid through GSTR-1 — it feeds the recipient's GSTR-2B and so directly affects whether your customers can claim input tax credit.
GSTR-3B is a self-assessed summary return under Section 39 read with Rule 61. It reports total outward liability, ITC availed, reverse-charge tax and the net cash payable, and it is the return through which the tax is paid. Tax liability is discharged only on filing GSTR-3B after offsetting ITC and cash.
Key differences at a glance
| Particulars | GSTR-1 | GSTR-3B |
|---|---|---|
| Nature | Outward supply statement | Summary return |
| Legal provision | Section 37, Rule 59 | Section 39, Rule 61 |
| Level of detail | Invoice-wise | Consolidated totals |
| Tax payment | No | Yes — tax is paid here |
| Effect on customer ITC | Direct (flows to GSTR-2B) | None |
| Monthly due date | 11th of next month | 20th of next month |
| QRMP frequency | Quarterly (IFF optional monthly) | Quarterly (22nd/24th) |
Due dates above are the standard ones; QRMP staggered 3B dates (22nd/24th) depend on the State. Verify the exact date for your State and period.
How the two returns interact
Since the sequential-filing rules and auto-population reforms, the system now pulls GSTR-1 data into GSTR-3B Table 3 as an editable draft, and pulls GSTR-2B into the ITC table. This makes reconciliation between GSTR-1 and GSTR-3B critical: any mismatch in outward liability is flagged in Form GSTR-1/3B comparison and can trigger a notice or recovery under Section 75(12).
Worked example. If your GSTR-1 reports outward tax of Rs.5,00,000 but GSTR-3B Table 3.1 shows Rs.4,60,000, the Rs.40,000 difference is treated as self-assessed tax not paid and can be recovered with interest under Section 50 without a show-cause notice.
Common mistakes for finance teams
- Reporting different outward values in GSTR-1 and GSTR-3B — always reconcile both monthly.
- Missing GSTR-1 because "no tax is due" — non-filing still blocks customer ITC and attracts late fee.
- Claiming ITC in 3B that is not reflected in GSTR-2B — from the Rule 36(4) / Section 16(2)(aa) regime, ITC is restricted to what appears in 2B.
- Editing auto-populated 3B figures without documenting why — keep a reconciliation working for audit.
Key takeaways
- GSTR-1 = invoice-level outward statement; GSTR-3B = summary return that pays the tax.
- GSTR-1 feeds customer GSTR-2B; GSTR-3B does not affect customer ITC.
- The two must reconcile — mismatches are recoverable under Section 75(12).
- ITC in 3B is restricted to what appears in GSTR-2B (Section 16(2)(aa)).