GSTR-1 Monthly + Quarterly Filing FY 2025-26 — Due Dates, Tables, IFF + E-Invoice Auto-Flow

🔔 IMS context (FY 2024-25 onwards): GSTN launched the Invoice Management System (IMS) on the GST portal from October 2024. Invoices reported by suppliers in GSTR-1 now flow to the recipient’s IMS dashboard where they must be ACCEPTED, REJECTED, or kept PENDING before auto-populating into the recipient’s GSTR-2B (and thus ITC eligibility). GSTR-9 for FY 2024-25 onwards includes IMS-based ITC auto-population fields per Notification No. 16/2025-Central Tax. This page covers GSTR-1 filing mechanics; the downstream IMS workflow is on the GSTR-2A vs 2B reconciliation page.

Why GSTR-1 matters

GSTR-1 is the invoice-level statement of outward supplies — the upstream piece of the GST return cycle. Where GSTR-3B is the consolidated summary that triggers tax payment, GSTR-1 is the detailed transaction-by-transaction declaration that flows into the GST network’s reconciliation engine and ultimately into every buyer’s GSTR-2B.

The consequence for SMEs is direct: late or inaccurate GSTR-1 filing blocks the buyer’s Input Tax Credit. In B2B commerce this surfaces as delayed vendor payments and damaged commercial relationships — buyers either withhold the GST component or stop transacting until the supplier’s GSTR-1 hygiene is restored.

For the broader GST framework context, see the GST overview pillar.

What GSTR-1 is

GSTR-1 reports:

• Every B2B invoice issued to a registered counterparty (invoice-level)
• Every inter-state B2C invoice above ₹2.5 lakh (invoice-level)
• Consolidated state-wise totals of all other B2C retail supplies
• Exports + supplies to SEZ units (invoice-level)
• Debit notes + credit notes issued during the period
• Amendments to prior-period filings
• An HSN-wise summary + a document-issued summary
• Tax-liable advances received and adjusted

No tax is paid when filing GSTR-1 — the return establishes the liability that is discharged via GSTR-3B.

Who files + frequency

Every regular GST taxpayer files GSTR-1. Exceptions:

• Composition Scheme dealers — file CMP-08 quarterly + GSTR-4 annually instead. See Composition Scheme Eligibility.
• Input Service Distributors (ISD) — file GSTR-6
• Non-Resident Taxable Persons — file GSTR-5
• OIDAR service providers — file GSTR-5A
• Tax deductors under Section 51 — file GSTR-7

Monthly vs Quarterly (QRMP)

• Aggregate turnover > ₹5 crore in PY OR opted out of QRMP → monthly GSTR-1
• Aggregate turnover ≤ ₹5 crore in PY + opted into QRMP → quarterly GSTR-1 + optional IFF in M1/M2

QRMP is opted-in / opted-out at the start of each quarter (or annually for stability) on the GST portal.

Due dates FY 2025-26

Monthly filers

• 11th of the following month
• Example: April 2025 outward supplies → file by 11 May 2025

QRMP filers — quarterly GSTR-1

• 13th of the month following the quarter
• Q1 (Apr-Jun) → 13 July, Q2 (Jul-Sep) → 13 October, Q3 (Oct-Dec) → 13 January, Q4 (Jan-Mar) → 13 April

QRMP filers — IFF (optional, M1 + M2)

• 13th of the next month for the B2B invoices uploaded that month
• Maximum ₹50 lakh aggregate value per month per GSTIN
• B2B invoices only (not B2C; not advances; not amendments)
• Optional — choosing not to use IFF defers the buyer’s ITC by up to a quarter

A Nil GSTR-1 can be filed via the SMS facility (send “NIL R1 [GSTIN] [period]” to 14409 from the registered mobile).

For end-to-end management of overlapping deadlines, see the GST Return Filing service.

Tables walkthrough

Table	What it captures	Reporting level
4	Taxable outward supplies to registered persons (B2B)	Invoice level — THIS table feeds buyers’ GSTR-2B
5	Taxable outward inter-state supplies to unregistered persons (B2C-Large > ₹2.5 lakh)	Invoice level
6	Zero-rated supplies (exports + supplies to SEZ) and Deemed Exports	Invoice level
7	Taxable outward supplies to unregistered persons (B2C — small + intra-state large)	Consolidated state-wise summary
8	Nil-rated, exempted, and non-GST outward supplies	Summary
9	Amendments to prior period (9A: B2B, 9B: B2C-Large, 9C: Exports)	Invoice level
10	Amendments to Table 7 (B2C-Small)	Consolidated
11	Advances received + advances adjusted against invoices	Consolidated by tax rate
12	HSN-wise summary of outward supplies	4-digit (≤ ₹5cr) or 6-digit (> ₹5cr) — see HSN/SAC codes spoke
13	Documents issued summary (invoices, credit notes, delivery challans — issued + cancelled serial range)	Summary by document type
14	Supplies through E-Commerce Operators (ECO) — including 9(5) liability split	Invoice / summary depending on supply type

Invoice Furnishing Facility (IFF) — QRMP optional benefit

QRMP creates a commercial problem for small suppliers selling B2B: if the supplier files GSTR-1 only at quarter-end (e.g., 13 July for the Apr-Jun quarter), the buyer’s GSTR-2B for April + May does not show the supplier’s invoices until July — delaying the buyer’s ITC by up to 3 months.

IFF solves this by allowing the QRMP supplier to upload B2B invoices monthly for months 1 and 2 of the quarter, on a strictly optional basis:

• Window: 1st to 13th of the next month
• Cap: ₹50 lakh aggregate value per month per GSTIN
• Coverage: B2B invoices + B2B credit/debit notes only — NOT B2C, advances, or amendments
• No re-entry needed: B2B invoices uploaded via IFF in M1/M2 are auto-rolled into the quarterly GSTR-1; the supplier files only the M3 + non-IFF residual in the quarterly return

Buyers receiving B2B supplies from QRMP suppliers commonly request the supplier to use IFF — the ITC-timing benefit is meaningful.

E-invoice integration

Taxpayers required to generate e-invoices (currently aggregate turnover > ₹5 crore from 1 August 2023) push invoice JSON payloads to the Invoice Registration Portal (IRP) to generate an Invoice Reference Number (IRN) BEFORE issuing the invoice to the customer. For e-invoicing mechanics in detail, see the E-Invoicing Applicability + Mechanics spoke.

The IRN-validated invoice data then auto-flows to GSTR-1 via the GSTN within ~2 days:

• Auto-populates: Table 4 (B2B), Table 6 (exports), Table 9 (amendments where the original was an e-invoice)
• Does NOT auto-populate: Tables 5, 7, 8, 10, 11, 12, 13, 14 (these still need ERP-side data entry)

Reconciliation discipline: despite the auto-flow, finance teams should compare the auto-populated GSTR-1 against the ERP sales register before filing. API failures, cancelled IRNs, and IRN-generated-but-not-billed invoices all show up at this reconciliation step.

GSTR-1 → GSTR-2B → buyer’s GSTR-3B flow

The chronological dependency that makes GSTR-1 timing commercially critical:

1. Supplier uploads B2B invoice into Table 4 of GSTR-1 (or IFF for QRMP M1/M2 case)
2. Cut-off: supplier files GSTR-1 by the 11th (monthly) or 13th (QRMP/IFF) of the next month
3. Statement generation: GSTN generates the static GSTR-2B for the buyer on the 14th of the next month, aggregating all supplier-uploaded invoices up to the 13th
4. Buyer’s GSTR-3B Table 4 auto-populates from GSTR-2B; the buyer’s ITC claim is bounded by what is in GSTR-2B
5. Buyer’s GSTR-3B due by the 20th (monthly) / 22nd or 24th (QRMP)

Missing the 11th/13th supplier deadline → invoice misses the current month’s GSTR-2B sweep → buyer’s ITC is deferred to the next month. For the buyer-side ITC mechanics, see the ITC Rules guide.

Late fee + amendment mechanism

Late fee — Section 47

• ₹50/day (₹25 CGST + ₹25 SGST) for a normal return; ₹20/day for a Nil return
• Capped at ₹5,000 per Act per return for standard taxpayers (lower caps for some categories per notifications)
• Late fee accrues until the return is filed; the next month’s return is blocked until the current one is filed (sequential filing rule)

No interest on GSTR-1 itself

Section 50 interest applies to delayed tax payment — and tax is paid via GSTR-3B. So late GSTR-1 attracts only the Section 47 late fee, not Section 50 interest.

Amendments — Table 9

Errors in a filed GSTR-1 cannot be “revised” — the return cannot be reopened once filed. Corrections happen via Table 9 of the next open GSTR-1:

• Table 9A — amendments to B2B invoices (Table 4) — wrong GSTIN, wrong invoice value, wrong tax rate, wrong place of supply
• Table 9B — amendments to B2C-Large invoices (Table 5)
• Table 9C — amendments to exports (Table 6)
• Table 10 — amendments to B2C-Small consolidated (Table 7)

The amendment carries an original-invoice-reference + revised-invoice-reference structure; the buyer’s GSTR-2B reflects the revised position once the amendment is filed.

Time limit on amendments: amendments to invoices of a financial year can be made until 30 November of the following FY OR the date of filing the annual return for that year (whichever is earlier) — same Section 16(4) cut-off as ITC claims.

Common GSTR-1 errors

1. B2B vs B2C misclassification — uploading a B2B invoice (where the buyer has a GSTIN) into Table 7 (B2C summary) because the accounting software didn’t capture the GSTIN. The buyer cannot see the invoice in their GSTR-2B and loses ITC. Surfaces during buyer’s reconciliation.
2. Wrong place of supply (POS) — for inter-state supplies, selecting the wrong state code routes IGST to the wrong state’s account; complex to correct via Table 9 amendments.
3. RCM-flag mismatch — supplying a service liable to reverse charge (e.g., GTA service) and reporting it in Table 4 without the RCM flag, OR with the wrong flag. See Reverse Charge Mechanism (RCM).
4. Missing Table 12 HSN summary — Table 12 is mandatory; HSN auto-population from e-invoice helps but doesn’t cover non-e-invoice B2C lines. Missing Table 12 triggers portal validation failure.
5. GSTR-1 vs GSTR-3B mismatch — declaring higher sales in GSTR-1 than the corresponding total in GSTR-3B Table 3.1. The portal cross-matches; sustained mismatch triggers Section 79 recovery proceedings on the under-declared tax.
6. Late B2B upload missing GSTR-2B cut-off — uploading B2B invoices after the 13th of the next month means buyers don’t see them until the following month’s GSTR-2B. Commercial-relationship damage.
7. Cancelled e-invoices still in GSTR-1 — e-invoice cancelled on IRP within 24 hours but the cancellation didn’t sync to GSTR-1; manual cleanup needed before filing.
8. Document series gap in Table 13 — Table 13 captures the issued + cancelled invoice serial range; gaps (e.g., missing invoice numbers) attract scrutiny.

For reconciliation of GSTR-1 + GSTR-3B + GSTR-2B + books, see the GST Reconciliation service.