What are the GST return due dates in 2026?

Regular scheme: GSTR-1 by 11th, GSTR-3B by 20th (monthly). QRMP: GSTR-1 quarterly by 13th, GSTR-3B by 22nd/24th (state-dependent). GSTR-9 by 31 December of following FY. Composition CMP-08 by 18th of month following quarter.

How do I file GSTR-3B without errors?

Follow the 22-minute checklist: reconcile 2B on the 12th, verify place of supply, audit HSN, capture RCM, move ITC-ineligible to 4(B), match ITC to 2B, then file. SaathiX ERP auto-prepares 90% of this from your books.

Is e-invoicing mandatory in 2026?

Yes for turnover > ₹5 Cr (some sectors > ₹1 Cr). Every B2B invoice must have an IRN + QR code from the IRP portal before printing. SaathiX ERP auto-generates IRN in under 2 seconds.

Should I opt for the QRMP scheme?

If turnover ≤ ₹5 Cr and your buyers are okay with quarterly filing, yes — you get 4 GSTR-1 and 4 GSTR-3B filings a year instead of 24. Tax payment stays monthly via PMT-06.

What is the difference between GSTR-9 and GSTR-9C?

GSTR-9 is the annual summary return (mandatory for turnover > ₹2 Cr). GSTR-9C is the reconciliation between books and GSTR-9 (mandatory for turnover > ₹5 Cr, self-certified from FY 2020-21).

Can SaathiX ERP file GST returns directly to the portal?

Yes — SaathiX ERP integrates with a licensed GSP (GST Suvidha Provider) to file GSTR-1, 3B and 9 directly. You can also export JSON and upload to the government portal manually.

GST Return Filing in 2026: The Complete Guide to GSTR-1, GSTR-3B and GSTR-9 for Indian SMBs

Every month, 12 million Indian businesses file GSTR-3B. After auditing 4,300 real returns filed via SaathiX ERP in Q2 2026, we can say with data: roughly a third are filed with errors that trigger notices six to nine months later. Most errors are avoidable.

This is the 2026 GST filing guide — organised by form (GSTR-1, 3B, 9), by scheme (regular, QRMP, composition), and by common error. Bookmark it before your next filing.

The 2026 GST return landscape at a glance

Regular scheme (turnover > ₹5 Cr) — Monthly GSTR-1 by the 11th, monthly GSTR-3B by the 20th, annual GSTR-9 + reconciliation GSTR-9C by 31 Dec of following FY.

QRMP scheme (turnover ≤ ₹5 Cr) — Quarterly GSTR-1 by the 13th of month following the quarter, quarterly GSTR-3B by the 22nd or 24th (state-dependent). Monthly PMT-06 payments in months 1 and 2.

Composition scheme (turnover ≤ ₹1.5 Cr / ₹75 L) — Quarterly CMP-08 by the 18th, annual GSTR-4 by 30 June.

E-commerce operators — GSTR-8 monthly, TCS related.

GSTR-1 — the outward supplies return

GSTR-1 reports every invoice you issued. It's the source of truth: your buyer's GSTR-2B (their ITC eligibility) is auto-populated from your GSTR-1. Get it wrong, they lose ITC, they call your accounts team.

What GSTR-1 contains

B2B invoices (with buyer GSTIN) — table 4

B2C large invoices (>₹2.5L interstate) — table 5

B2C small invoices (rate-wise summary) — table 7

Exports (with LUT/bond details) — table 6A

Credit + debit notes — tables 9A/9B

HSN summary — table 12

Documents issued — table 13

Common GSTR-1 errors we see monthly

Error 1: Wrong place of supply. Interstate vs intrastate decides CGST+SGST vs IGST. Wrong PoS = wrong tax split = your buyer's 2B shows one number, their books show another.

Error 2: HSN below 6 digits for > ₹5 Cr turnover. From Apr 2026, 8-digit HSN is mandatory for turnover > ₹5 Cr. Below that, 4-digit for B2B.

Error 3: Missing e-invoice IRN. If your turnover crossed ₹5 Cr in any FY since 2017-18, e-invoice is mandatory. Missing IRN = invoice invalid = buyer can't claim ITC.

Error 4: Credit notes booked in wrong month. A credit note issued in October for a September invoice must appear in October's GSTR-1 (not September's). Backdating is not allowed.

Error 5: Advance received not reported. If you received advance and didn't ship by month-end, you owe GST on the advance — reportable in table 11.

GSTR-3B — the summary return

GSTR-3B is the summary of your tax liability and ITC claim for the month. It's what actually gets you a tax payment or a refund.

Structure of GSTR-3B

Table 3.1 — outward supplies (taxable, zero-rated, exempt)

Table 3.1.1 — supplies u/s 9(5) (e-commerce)

Table 3.2 — interstate supplies to unregistered buyers

Table 4 — ITC claimed (A) eligible, (B) reversed, (C) net available, (D) ineligible

Table 5 — exempt inward supplies

Table 6.1 — tax payment

The 22-minute GSTR-3B checklist

Step 1: Reconcile GSTR-2A / 2B first (do this on the 12th, not the 19th). Auto-populated 2B lags supplier filing by up to a week. Chase missing suppliers early via WhatsApp — 40%+ respond within 48 hours.

Step 2: Verify place of supply on every B2B invoice. Interstate vs intrastate is the single biggest source of tax reversal notices.

Step 3: Audit HSN classification. Wrong HSN = wrong rate = notice.

Step 4: Reverse charge (line 3.1(d)). Lawyer fees, unregistered GTA, director sitting fees, security services, sponsorship — all attract RCM.

Step 5: Move ITC-ineligible entries to 4(B). Motor vehicles (except goods carriage), personal insurance, staff welfare above statutory — all belong in 4(B).

Step 6: Match ITC claimed vs 2B. From Jan 2022 onwards, ITC claim > 2B is not allowed (Rule 36(4) tightened to 0%). Excess claim triggers reversal notice.

Step 7: File before 20th (regular) or 22nd/24th (QRMP). Late filing attracts ₹50/day (₹20 for nil) + 18% interest on tax component.

GSTR-9 — the annual return

GSTR-9 reconciles your books, your GSTR-1s, your GSTR-3Bs and your 2A/2Bs for the full FY. It's due 31 December of the following FY (so FY 2025-26 due 31 Dec 2026).

Who has to file GSTR-9?

Turnover > ₹2 Cr — GSTR-9 mandatory.

Turnover ₹2-5 Cr — GSTR-9 mandatory; GSTR-9C optional (self-certified from FY 2020-21).

Turnover > ₹5 Cr — GSTR-9 + GSTR-9C (reconciliation) both mandatory.

The 5-step GSTR-9 prep

1. Reconcile books turnover with GSTR-1 turnover. Any gap = notice bait.

2. Reconcile ITC in books with 3B claimed with 2A/2B. Three numbers, must reconcile.

3. Report HSN wise summary of outward supplies. Table 17.

4. Report HSN wise summary of inward supplies (optional but recommended). Table 18.

5. Pay any additional tax via DRC-03. GSTR-9 has no payment field — you pay via DRC-03 before filing.

E-invoice + e-way bill — the compliance backbone

E-invoice (IRN) — Mandatory for turnover > ₹5 Cr since Aug 2023, extended to > ₹1 Cr in some sectors. Every B2B invoice must be uploaded to IRP (Invoice Registration Portal) and receive an IRN + QR code before printing. Miss the IRN, invoice is invalid.

E-way bill — Required for movement of goods > ₹50,000 (₹1L intra-Delhi, varies by state). Generated on the e-way bill portal or via API, valid for 1 day per 200 km.

SaathiX ERP auto-generates both — IRN in under 2 seconds, e-way bill in 5. No manual portal navigation.

The QRMP scheme — is it right for you?

QRMP (Quarterly Return, Monthly Payment) was launched in 2021 for turnover ≤ ₹5 Cr. You file GSTR-1 and GSTR-3B quarterly but pay tax monthly via PMT-06.

Pros of QRMP

Only 4 GSTR-1 and 4 GSTR-3B filings a year (vs 24).

IFF (Invoice Furnishing Facility) lets you upload B2B invoices monthly for buyer ITC.

Fixed-sum payment option in first 2 months of quarter.

Cons of QRMP

Buyers may prefer suppliers on monthly filing (their ITC lands faster).

Quarterly reconciliation is heavier — 3 months of errors at once.

For most retailers < ₹5 Cr, QRMP is worth it — SaathiX ERP supports it natively.

Common notices and how to handle them

Notice under Section 61 (scrutiny of return) — Officer thinks GSTR-3B doesn't tie to GSTR-1 or books. Reply within 30 days with reconciliation.

Notice under Rule 36(4) / 88C / 88D — ITC claimed > 2B. Either reverse the excess with interest, or prove the mismatch.

Notice under Section 74 — Fraud, wilful misstatement or suppression. Serious — engage a CA immediately.

Notice under Section 65 (audit) — Random or trigger-based full audit. Preparation: reconciled books, filed returns, supplier confirmations for ITC claims.

SaathiX ERP has a Notice Management module that stores every notice, drafts a first reply and tracks deadlines.

Composition scheme — the ₹1.5 Cr shortcut

Composition allows turnover up to ₹1.5 Cr (₹75 L for special-category states) to pay a fixed % of turnover: 1% for manufacturers, 1% for traders, 5% for restaurants, 6% for other services.

Pros — Simple CMP-08 quarterly, no ITC hassle.

Cons — Can't sell interstate (services can as of 2023), can't charge GST to buyer, can't claim ITC. Buyer can't take ITC either — so B2B customers avoid composition suppliers.

Best for: pure B2C small retail, restaurants, small services.

How SaathiX ERP auto-prepares your returns

The manual method: download 2A/2B, paste into Excel, reconcile, format for GSTR-1 upload, upload, verify.

The SaathiX ERP method:

1. Every bill you generate has GSTIN, HSN, PoS, IRN already baked in.

2. GSTR-1 auto-generates from your invoices — one click.

3. 2A/2B auto-download and reconcile against your purchase register — mismatches flagged.

4. GSTR-3B tables populate from books — table 3.1, 4(A), 4(B), 5, RCM all auto-filled.

5. File directly via GSP integration, or export JSON for the portal.

6. Notice inbox monitored 24x7 — you get a WhatsApp alert if a notice lands.

Median GSTR-3B prep time drops from 4 hours to 22 minutes.

Free vs paid — what you actually need

SaathiX ERP's free tier includes GSTR-1 export and 3B tables generation from books. Paid tiers unlock direct GSP filing, 2B reconciliation, notice management, and free CA read-only access.

Getting started — file your next return in SaathiX ERP

1. Sign up and add your GSTIN.

2. Import your last 3 months of sales and purchases (or start fresh from this month).

3. On the 12th, run the 2B match report — chase missing suppliers.

4. On the 19th, run the GSTR-3B checklist — 22 minutes.

5. File. Get an SMS confirmation. Move on.

The bottom line

GST is not the beast it was in 2017. In 2026, with the right software, compliance is a 30-minute-a-month exercise, not a full-time job. The businesses that treat it that way — auto-prep, auto-reconcile, auto-file — get audited less, get notices less, and sleep better.