GST Return Filing

GST returns are not one form — they are a connected monthly cycle where your sales register, e-invoice IRN log, vendor invoices, GSTR-2B credit and bank payments all have to tie out by the 20th. Miss a single thread and the cost compounds: ₹50-a-day late fees, 18% interest on cash tax, blocked ITC for your customers, and a Rule 86A flag that can freeze your electronic credit ledger overnight.

For FY 2026-27 the cycle is tighter than ever. The Invoice Management System (IMS) now sits between your supplier's GSTR-1 and your GSTR-2B, GSTR-3B values are hard-locked from auto-populated figures, and ITC reclaims under Rule 37A run on a stopwatch. You need filing that is calendar-driven and reconciled monthly — not a scramble on the 19th.

At a Glance

• Who needs it: Every regular GST registrant — proprietors, LLPs, private limited companies and composition dealers — must file the returns their registration category requires.
• Governing law: CGST Act 2017, IGST Act 2017, respective State GST Acts and the CGST Rules 2017 read with current CBIC notifications.
• Returns covered: GSTR-1, GSTR-1A, GSTR-3B, GSTR-9, GSTR-9C, CMP-08, IFF and ITC-04 for job-work.
• Turnaround: Onboarding in 3-5 working days; monthly filing cycle thereafter; annual return window October to December.
• Key thresholds: ₹5 crore for e-invoicing and GSTR-9C; ₹2 crore for GSTR-9; ₹5 crore for QRMP eligibility.
• Filing cadence: Monthly for turnover above ₹5 crore; quarterly under QRMP with monthly PMT-06 tax payment for everyone else.
• Annual return: GSTR-9 and GSTR-9C due 31 December following the close of the financial year.

What's New for FY 2026-27

A few procedural changes have reshaped the monthly cycle. They affect how credit is claimed, how returns are corrected and how scrutiny opens.

• IMS is live: The Invoice Management System now lets you accept, reject or keep pending each supplier invoice before it lands in GSTR-2B. Action is required — silence equals acceptance, and a rejected invoice removes the credit for that cycle.
• GSTR-1A in play: The amendment return introduced in 2024 is now standard practice. It lets you correct GSTR-1 figures within the same month before GSTR-3B is filed, instead of waiting for the next return.
• GSTR-3B hard-locked: Tax liability and ITC fields in Tables 3 and 4 of GSTR-3B are now auto-populated from GSTR-1 and GSTR-2B, with limited override. Reconciliation has to happen before filing, not after.
• 30 November ITC limitation: Section 16(4) caps the right to claim ITC for an invoice at 30 November of the following FY or the date of GSTR-9, whichever is earlier. The annual sweep is non-negotiable.
• Section 128A waiver closed: The one-time waiver scheme for FY 2017-18 to 2019-20 demands closed in March 2025. Old demands not settled then are now in regular recovery mode.
• TCS for e-commerce operators: Rate confirmed at 0.5% (0.25% CGST + 0.25% SGST). Sellers reconcile TCS credit in GSTR-2B before claiming.

Who Needs Which Return Set

GST filing isn't a single product — your category and turnover decide the form set. Here's who picks which.

• Regular taxpayer above ₹5 crore: Monthly GSTR-1 by the 11th, monthly GSTR-3B by the 20th, e-invoicing for every B2B invoice, GSTR-9 and GSTR-9C by 31 December.
• Regular taxpayer ₹2-5 crore: Same monthly returns, but no e-invoicing. GSTR-9 mandatory; GSTR-9C optional unless turnover crosses ₹5 crore mid-year.
• QRMP filer (up to ₹5 crore): Quarterly GSTR-1 and GSTR-3B, monthly PMT-06 challan, optional IFF for the first two months of each quarter to keep B2B customers happy.
• Composition dealer: Quarterly CMP-08 challan-cum-statement and annual GSTR-4. No ITC, fixed-rate tax, simplified bookkeeping.
• Exporter (with or without LUT): GSTR-1 with Table 6A for exports, refund applications in RFD-01, and shipping bill matching for IGST refund.
• Input Service Distributor: Monthly GSTR-6 for credit distribution to branches under the same PAN.
• E-commerce operator: GSTR-8 for TCS collected on supplies made through the platform.

How It Actually Works

A clean monthly cycle has six moving parts. Each one has to close before the next begins, otherwise the error carries forward into the annual return.

Step 1: Onboarding and Calendar Lock

We capture your GSTIN list, turnover bracket, QRMP option, e-invoicing applicability and the filing officer mapped at each location. From there we build a due-date calendar covering GSTR-1, GSTR-3B, PMT-06, IFF, GSTR-9 and any state-specific obligations like profession tax that often sit in the same shared services calendar.

The first three to five working days are about confirming registrations are clean and the filing dashboard is reconciled to last month's closing position. Any open exposure from prior periods is documented before the first new return is filed.

Step 2: Outward Supply and GSTR-1

Sales registers and e-invoice IRN logs are consolidated, credit and debit notes folded in, and B2B / B2C / export / SEZ buckets tagged. The draft GSTR-1 is reviewed against the e-invoice portal log to catch cancelled IRNs, late-generated IRNs and skipped invoices.

We file by the 11th of the following month — earlier for exporters waiting on IGST refund through the customs ICEGATE pipeline.

Step 3: ITC Reconciliation Against GSTR-2B and IMS

GSTR-2B is downloaded after the 14th. Books are matched invoice-wise. The IMS dashboard is used to accept matched invoices, keep mismatches pending for vendor follow-up, and reject duplicates or wrong-GSTIN entries.

Suppliers who didn't file GSTR-1 are flagged. Rule 37A reversal is computed for invoices where the supplier hasn't yet paid tax through GSTR-3B, and a reclaim ledger is updated for the cycle in which they do.

Step 4: GSTR-3B Tax Computation and Filing

Outward tax, RCM cash liability, eligible ITC, ineligible ITC, blocked credit and reversals are computed. Auto-populated values from the portal are reconciled to the books — variances explained line-by-line.

Challans are paid in cash where required, ITC offset where allowed, and GSTR-3B filed by the 20th. A one-page reconciliation memo goes to the management each cycle.

Step 5: GSTR-1A Amendments Within the Same Cycle

If a sales invoice was missed, miscoded or wrongly cancelled, GSTR-1A is filed before GSTR-3B for that month. This keeps the recipient's GSTR-2B clean and avoids the painful next-month correction cycle.

We use GSTR-1A as a discipline tool, not a fix-up — most clients only need it once or twice a year.

Step 6: Annual Return — GSTR-9 and GSTR-9C

Between October and December, we tie GSTR-1, GSTR-3B and the books to the audited financials. Turnover, ITC, RCM, exports and exempt supply are reconciled. GSTR-9 is filed; GSTR-9C is self-certified with the reconciliation statement attached.

This is when the September and October GSTR-3B has already captured the Section 16(4) ITC sweep, so nothing stranded slips past the 30 November limitation.

Step 7: Notice and Scrutiny Defence

If ASMT-10, DRC-01A or DRC-01 lands, we respond from the same working papers used for filing. Section 75(4) personal hearing is attended; first appeal under Section 107 is drafted where required.

Filing and defence share one file — not two. That single audit trail is what makes a notice answerable in days, not weeks.

A Real Example: Maya Textiles Pvt Ltd

To see how the cycle works in numbers, consider Maya Textiles Pvt Ltd, a Surat-based manufacturer with ₹12 crore annual turnover and B2B customers across five states.

• Outward supplies for June 2026: ₹1.05 crore taxable value, 5% GST = ₹5.25 lakh output tax. All B2B, all e-invoiced. GSTR-1 filed 11 July.
• Inward supplies: ₹78 lakh of raw cotton, services and capital goods. GSTR-2B shows ₹4.21 lakh of ITC, of which ₹15,000 is from a supplier who hasn't filed GSTR-3B by the cut-off.
• IMS action: 41 invoices accepted, 2 kept pending (vendor follow-up for missing GSTIN), 1 rejected (duplicate).
• Rule 37A reversal: ₹15,000 reversed in June GSTR-3B; reclaim flagged for the month the supplier files.
• RCM: ₹22,000 paid in cash on legal fees and import-of-services; same ₹22,000 claimed as ITC in the same return.
• Net cash tax: Output tax ₹5.25 lakh minus eligible ITC ₹4.06 lakh = ₹1.19 lakh paid via challan. GSTR-3B filed 18 July.

Two weeks later the pending vendor files GSTR-1, the invoice flows to July's GSTR-2B, and the reclaim of the earlier ₹15,000 enters the July return. Nothing is lost — it is just timed.

Annual Cycle — What Backs Up Each Return

A filed return is only as defensible as the working papers behind it. Each return in the cycle has a specific reconciliation that must survive scrutiny three to five years later.

• GSTR-1 backed by: E-invoice IRN log, sales register, credit / debit notes register, e-Way bill log and export shipping bill copies.
• GSTR-3B backed by: Outward tax computation, ITC ledger, RCM register, blocked credit working, Rule 42 / 43 reversal computation and challan copies.
• GSTR-9 backed by: Books-to-returns reconciliation, audited financials, turnover bridge, ITC bridge and the September-October ITC sweep memo.
• GSTR-9C backed by: Self-certified reconciliation between audited financials and annual return, with reasons for every reconciling item.
• Refund claims backed by: RFD-01 with shipping bills, FIRC / BRC for service exports, and inverted-duty-structure working under Rule 89(5) where applicable.

Working papers are the single biggest difference between a closed scrutiny and a multi-year demand. Build them at filing, not at notice.

Where It Goes Wrong

A pattern of small errors creates 80% of all GST notices. These are the ones we see most.

• ITC before GSTR-2B: Claiming credit before the invoice appears in GSTR-2B bars provisional credit and triggers Rule 36(4) departures that the IMS now polices automatically.
• Missing the 30 November cut-off: Invoices from the prior FY that aren't claimed by then lapse permanently under Section 16(4) — no second chance.
• No Rule 37 reversal on unpaid vendors: ITC not reversed when a vendor isn't paid within 180 days is a silent error that surfaces during scrutiny years later.
• RCM paid through ITC offset: Reverse-charge tax must be paid in cash. Tax officers reject ITC-offset claims and demand cash payment with interest.
• Turnover mismatch in GSTR-9: Confusing GSTR-9 turnover with audited turnover — both must reconcile to the audited financials with a documented bridge.
• Missing IMS action: A no-action invoice is deemed accepted, but rejecting an invoice that should have been kept pending wipes out legitimate credit.
• Wrong place of supply: CGST + SGST claimed on inter-state services where IGST was due — leads to cross-utilisation disputes and demands.
• Skipping nil returns: Even zero-activity months attract ₹20-per-day late fee plus blocking risks for the GSTIN.

What You Receive at the End

• Filed GSTR-1, GSTR-3B and (where applicable) GSTR-1A acknowledgements for every cycle
• IMS action log with accept / pending / reject decisions for each invoice
• Monthly ITC reconciliation memo against GSTR-2B, with Rule 37A reversal and reclaim ledger
• e-invoice IRN log reconciled to GSTR-1
• RCM register split by vendor category — GTA, legal, import-of-services, director sitting fees
• Tax challans (CGST, SGST, IGST, Cess) and PMT-06 records under QRMP
• Annual GSTR-9 and self-certified GSTR-9C with working papers and reconciliation statement
• Notice and scrutiny file — ASMT-10, DRC-01A, DRC-01 responses, hearing notes, appeals
• Year-end summary tying turnover, ITC and RCM to the audited financials

How to Get Started

Filing begins with onboarding. Share your GSTIN list, the last six months of returns, and read-only access to your accounting software. We complete a baseline reconciliation, identify any open exposures from prior periods, and set up the filing calendar within five working days.

From the next due date onwards, the cycle runs on its own schedule — you see a clean monthly memo, a tax-payment instruction by the 18th, and a filed acknowledgement before midnight on the 20th. Annual return work begins in October, well before the 31 December cut-off, and any IMS or GSTR-2B drift gets caught in the same cycle it appears.