GST Consultant in Mumbai: 2025-26 Guide to Compliance, ITC Protection & Notice Support by CA Murli Chandak, FCA

In short: CA Murli Chandak is a Chartered Accountant (FCA) who manages GST compliance end to end for businesses across Mumbai and the wider Mumbai Metropolitan Region — registration, monthly and quarterly return filing, GSTR-2B and Invoice Management System (IMS) based Input Tax Credit reconciliation, e-invoicing and e-way bill compliance, annual returns and replies to departmental notices. The 2025-26 changes — the new 2-slab rate structure, the locked GSTR-3B, the IMS credit-note rules and the 3-year bar on filing old returns — are built into the monthly process rather than discovered after a notice arrives. The first 30-minute consultation is free.

Contents
1. Why GST Compliance in Mumbai Now Needs More Than a Return-Filer
2. What Changed in GST for 2025-26 — and Why It Matters for Your Filings
3. GST Registration in Mumbai: Who Needs It and How It Is Handled
4. The Monthly Compliance Cycle: How Your Returns Are Actually Prepared
5. Input Tax Credit: Reconcile It Before It Becomes a Notice
6. E-Way Bills and Movement of Goods in Maharashtra
7. GST Notices, Scrutiny and Departmental Proceedings
8. Annual Returns and the Year-End Close
9. Who CA Murli Chandak Works With in Mumbai
10. Fees and How an Engagement Starts
11. Why Work With CA Murli Chandak
12. Frequently Asked Questions

1. Why GST Compliance in Mumbai Now Needs More Than a Return-Filer

For most of GST’s first 8 years, the system quietly forgave sloppy processes. If the sales register and GSTR-1 did not match, the summary figures in GSTR-3B could be edited at the last minute. If a return was missed, it could be filed years later with a late fee. Input Tax Credit was claimed first and reconciled later, if at all.

That slack is gone. From the July 2025 tax period, the tax liability in GSTR-3B is auto-populated from GSTR-1 and locked. From 1 October 2025, a return whose due date is more than 3 years old is permanently barred from filing. The Invoice Management System now sits between your supplier’s filing and your ITC. And from 22 September 2025, the rate structure itself changed, forcing every business to re-map its products and services.

For a business in Mumbai — where transaction volumes tend to be higher and counterparties more numerous than in smaller cities — this shift matters more, not less. A trading firm in Kalbadevi, an NBFC in BKC or a manufacturer supplying across the Mumbai Metropolitan Region all generate enough monthly invoice volume that reconciliation has to be a routine, not a year-end exercise.

This is the way CA Murli Chandak runs GST engagements for Mumbai clients, as part of a broader taxation practice: a structured monthly cycle with reconciliation at the front, delivered digitally, so that filing at the end is a formality rather than a scramble. The sections below explain what changed in 2025-26, what each part of the compliance process involves, and how an engagement works.

2. What Changed in GST for 2025-26 — and Why It Matters for Your Filings

The 12 months to March 2026 brought the largest set of structural GST changes since the tax was introduced. If your compliance process was built before these changes, it is worth a review.

2.1 The New Rate Structure from 22 September 2025

The 56th GST Council meeting, held on 3 September 2025, approved a rationalised rate structure effective 22 September 2025. The 12% and 28% slabs were removed. Most goods and services now sit in 2 main slabs — 5% and 18% — with a 40% rate reserved for specified luxury and demerit goods such as large passenger vehicles, aerated beverages and online money gaming. Individual life and health insurance policies became exempt, and the special 3% and 0.25% rates for precious metals and stones continue — relevant for Mumbai’s jewellery and bullion trade specifically. Tobacco, pan masala and related products stay at 28% plus compensation cess until the cess-linked loan obligations are cleared, after which they move to the 40% slab.

The work this created was not just repricing. Every product and service line had to be re-mapped to the new rates, billing and accounting systems updated, time-of-supply rules applied correctly to transactions straddling 22 September 2025, and the ITC position reviewed — a rate cut alone does not trigger ITC reversal, but supplies that turned exempt from that date do. Errors made during that transition window are precisely what departmental scrutiny will focus on over the next 2 to 3 years.

2.2 GSTR-3B Is Now Locked to Your GSTR-1

From the July 2025 tax period (filed in August 2025), the auto-populated tax liability in GSTR-3B is non-editable, per GSTN advisories dated 7 June 2025 and 19 July 2025. The liability flows directly from GSTR-1, GSTR-1A or the Invoice Furnishing Facility (IFF), and Table 3.2 — inter-State supplies to unregistered persons, composition taxpayers and UIN holders — is equally locked.

If GSTR-1 was wrong, correction now runs through Form GSTR-1A, filed for the same tax period before GSTR-3B, or through an amendment in the following period’s GSTR-1/IFF. In practice, the sales reconciliation businesses used to complete after filing must now happen before the 11th of the month.

2.3 The Invoice Management System (IMS)

The IMS on the GST portal lets you accept, reject or keep pending each invoice, credit note and amendment your suppliers report. Only accepted or deemed-accepted documents flow into your GSTR-2B and, from there, into your ITC. Per GSTN Advisory No. 628 dated 8 October 2025, GSTR-2B continues to be auto-generated on the 14th of each month and ITC continues to auto-populate into GSTR-3B — but you can act on IMS records after GSTR-2B is generated and regenerate it before filing.

From the October 2025 tax period, credit notes and specified amendments can be kept pending for 1 tax period (1 quarter for quarterly filers), and on accepting a credit note you can restrict the ITC reversal to the credit actually availed, with remarks recorded on rejection or pending status. For a Mumbai business dealing with a large supplier base, IMS is where supplier discipline either gets enforced monthly or quietly erodes your ITC through deemed acceptance.

2.4 The 3-Year Bar on Filing Old Returns

The Finance Act, 2023 amended Sections 37, 39, 44 and 52 of the CGST Act (in force from 1 October 2023 via Notification No. 28/2023–Central Tax) to bar returns from being filed more than 3 years after their due date. GSTN phased this onto the portal through the second half of 2025 — after earlier target dates slipped, the restriction went live from 1 December 2025 — and any return — GSTR-1, GSTR-1A, GSTR-3B, GSTR-4, GSTR-5, GSTR-5A, GSTR-6, GSTR-7, GSTR-8 or GSTR-9/9C — whose due date is 3 or more years past stands permanently barred, on a rolling monthly basis.

Any Mumbai business with old unfiled periods — a dormant GSTIN, a branch registration in another State, a composition period left hanging — should get those reviewed and regularised without delay, because the window closes month by month and does not reopen.

2.5 E-Invoicing: The Rs 5 Crore Threshold and the 30-Day Reporting Window

E-invoicing applies to taxpayers whose aggregate annual turnover (AATO, computed at PAN level across all GSTINs) has exceeded Rs 5 crore in any financial year since 2017-18 — so a business that first crossed Rs 5 crore in FY 2025-26 came into the net from 1 April 2026. Separately, from 1 April 2025, taxpayers with AATO of Rs 10 crore or more must report invoices, credit notes and debit notes to the Invoice Registration Portal within 30 days of the document date; the IRP rejects documents older than 30 days, and a rejected document has no IRN and is not a valid tax invoice.

2.6 Annual Returns: The Rs 2 Crore Exemption Is Now Permanent

Notification No. 15/2025–Central Tax dated 17 September 2025 made the GSTR-9 exemption for taxpayers with aggregate turnover up to Rs 2 crore permanent, from FY 2024-25 onwards. GSTR-9C, the self-certified reconciliation statement, continues to apply above Rs 5 crore. The FY 2024-25 forms were also revised (Notifications No. 13/2025 and 16/2025–Central Tax) to align ITC reporting with IMS data and add new reversal disclosures. For FY 2025-26, the due date for both forms is 31 December 2026.

Change	Effective	Who it affects
2-slab rate structure (5% / 18%) plus 40% demerit rate	22 September 2025	All registered taxpayers
GSTR-3B auto-populated liability locked; corrections via GSTR-1A	July 2025 tax period	All GSTR-3B filers
IMS pending option for credit notes and adjustable ITC reversal	October 2025 tax period	All ITC-claiming taxpayers
Returns barred 3 years after their due date	Portal enforcement from 1 October 2025, rolling monthly	Anyone with unfiled old periods
30-day IRP reporting window for e-invoices	1 April 2025	AATO Rs 10 crore and above
GSTR-9 exemption up to Rs 2 crore made permanent; revised GSTR-9/9C formats	FY 2024-25 onwards	Annual return filers

3. GST Registration in Mumbai: Who Needs It and How It Is Handled

Registration under Section 22 of the CGST Act is required once aggregate turnover crosses Rs 40 lakh for suppliers of goods or Rs 20 lakh for suppliers of services (Maharashtra follows the normal-category thresholds, not the lower special-category limits). Section 24 makes registration compulsory regardless of turnover in specified cases — among them, persons making inter-State taxable supplies of goods, casual taxable persons, persons liable under reverse charge, agents supplying on behalf of others, and persons supplying through e-commerce operators, subject to the notified relaxations. Eligible small businesses can instead opt for the composition scheme — broadly up to Rs 1.5 crore turnover under Section 10, or Rs 50 lakh for service providers under Section 10(2A) — trading lower compliance for a flat levy and no ITC.

Because the trigger depends on the nature of supplies rather than turnover alone, CA Murli Chandak starts every registration engagement with an assessment of whether registration is actually required, and under which category, before the application itself — PAN and Aadhaar-linked verification, proof of the principal place of business, bank details, constitution documents for companies, LLPs, firms or trusts, and authorised-signatory details. Mumbai-registered applications (State code 27) routinely attract clarification notices where documents are inconsistent, particularly on address proof for shared or virtual office spaces common in the city’s commercial districts; these are handled within the prescribed process so the GSTIN is not delayed or rejected.

Registration is also where the compliance framework is set. Once the GSTIN is issued, the applicable return calendar is fixed, the invoice format is set up correctly, e-invoicing applicability is checked against PAN-level turnover, and the books are structured so monthly reconciliation is possible from the first return.

4. The Monthly Compliance Cycle: How Your Returns Are Actually Prepared

A GST return is only as good as the process behind it. For regular monthly filers, the cycle CA Murli Chandak runs looks like this:

a. Books first. Sales and purchase registers for the month are closed and tied to invoices, credit notes and debit notes. b. GSTR-1 by the 11th. Outward supplies are reconciled to the sales register — invoice-level values, GSTINs, tax rates and HSN codes — before GSTR-1 is filed, because these figures become the locked liability in GSTR-3B. c. IMS and GSTR-2B on the 14th. Supplier-reported invoices and credit notes are reviewed in the IMS — accepted, rejected or kept pending — and GSTR-2B is regenerated if actions are taken after the 14th. d. Purchase reconciliation. The purchase register is matched to GSTR-2B; gaps go to suppliers the same week, while they can still amend. e. GSTR-1A if needed. Any error found in the outward figures is corrected through GSTR-1A before GSTR-3B is filed. f. GSTR-3B and payment by the 20th (the 22nd of the month following the quarter for Maharashtra-registered QRMP taxpayers, which falls in the CBIC’s Category X group), with the tax computation and challan documented and acknowledgements preserved.

Businesses with turnover up to Rs 5 crore can opt for the QRMP scheme — quarterly GSTR-1 and GSTR-3B with the optional Invoice Furnishing Facility for B2B invoices in the first 2 months and monthly tax payment through PMT-06. Composition taxpayers file quarterly CMP-08 and an annual GSTR-4. Which structure suits a business depends on its customers, cash flow and volumes — reviewed at onboarding rather than defaulted.

5. Input Tax Credit: Reconcile It Before It Becomes a Notice

ITC is where most GST disputes now originate, because the department can see the mismatch before you do. Credit is available only where the statutory conditions are met — a valid tax invoice, receipt of goods or services, the supplier having reported the supply so it appears in your GSTR-2B, and payment to the supplier within 180 days — and subject to the blocked-credit categories in Section 17(5), such as motor vehicles (with exceptions), food and beverages, works-contract services for immovable property, and goods or services used for personal consumption.

A monthly ITC discipline has 4 layers. First, purchase invoices are matched to GSTR-2B, and differences are classified — supplier not filed, wrong GSTIN quoted, wrong tax amount, timing difference, or a genuine omission. Second, IMS actions are taken deliberately: rejecting wrong documents, keeping disputed credit notes pending within the permitted window, and adjusting credit-note reversals to the ITC actually availed. Third, expense heads are screened against Section 17(5) so blocked credits never enter the claim. Fourth, the paper trail — invoices, e-invoice IRNs where applicable, payment proof, reconciliation statements — is preserved so a mismatch intimation or scrutiny notice is answered with an attachment, not an investigation.

Done monthly, this catches supplier defaults while the supplier can still fix them. Done annually, it usually surfaces problems only after the ITC has already been claimed — precisely the situation the 2025-26 system is designed to catch.

6. E-Way Bills and Movement of Goods in Maharashtra

Movement of goods above the general Rs 50,000 threshold requires an e-way bill. Maharashtra additionally requires an e-way bill for intra-State movement of goods valued above Rs 1 lakh (Notification No. 15E/2018–State Tax under Rule 138(14)(d) of the MGST Rules, effective 1 July 2018) — a higher intra-State threshold than the general rule, and one that should be checked transaction by transaction rather than assumed, since it has not been revised despite periodic rumours of a lower cut-off.

Compliance here is operational: the invoice or e-invoice, transporter and vehicle details, and the e-way bill must tie together, and validity periods must be respected, because errors surface at the least convenient moment — a vehicle held up at a check post or in transit through the city’s congested freight corridors. For clients moving goods regularly in and out of Mumbai and the wider MMR, CA Murli Chandak sets up the generation workflow, trains despatch staff on the information required, and keeps the documentation aligned with the GST records so the movement trail matches the return trail.

7. GST Notices, Scrutiny and Departmental Proceedings

Departmental communications now arrive largely because the system found a mismatch: GSTR-1 versus GSTR-3B, GSTR-2B versus the ITC claimed, e-way bill data versus reported supplies, or returns simply not filed. Common categories include registration clarification notices, non-filing reminders, scrutiny notices in Form ASMT-10 seeking explanations for discrepancies in returns, ITC mismatch intimations, show-cause notices and demand orders, suspension or cancellation proceedings, departmental audit under Section 65 (with 15 working days’ prior notice) and, in specified cases, special audit under Section 66 by a nominated Chartered Accountant or Cost Accountant.

The handling process is consistent: read the notice and diarise the deadline on day 1; reconcile the exact period and issue raised; assemble the documentary support — invoices, returns, challans, reconciliations, ledger extracts; and file a reasoned reply within time, escalating to the first-appeal stage where an adverse order needs to be contested. Two things make matters worse and are avoidable: ignoring the notice, and replying without reconciling first. And one change makes old housekeeping urgent — with the 3-year filing bar now in force, an unfiled period that could once be quietly regularised may soon be impossible to file at all.

8. Annual Returns and the Year-End Close

For taxpayers above Rs 2 crore aggregate turnover, GSTR-9 consolidates the year’s outward supplies, ITC and tax payments; above Rs 5 crore, the self-certified GSTR-9C reconciles those figures to the audited financial statements. The revised formats applicable from FY 2024-25 pull ITC data on an IMS-aligned basis and require more granular reversal disclosures, so the annual filing is now a genuine reconciliation exercise between books, GSTR-1, GSTR-3B and GSTR-2B, not a copy-paste of the monthly returns. Late filing attracts a fee of Rs 200 per day (Rs 100 CGST plus Rs 100 SGST), capped with reference to turnover.

CA Murli Chandak treats the annual return as the year-end close of the GST ledger: differences between books and returns are identified, explained or corrected within the permitted mechanisms, and the working papers are retained so the same reconciliation serves the statutory audit, the income-tax filing and any future GST proceeding. For FY 2025-26, both forms fall due on 31 December 2026 — and the businesses that find December easy are the ones whose months were reconciled as they happened.

9. Who CA Murli Chandak Works With in Mumbai

Mumbai’s GST base is unusually varied, and the practice’s clients reflect that. Financial and professional services firms — NBFCs, broking and advisory outfits, insurance intermediaries clustered around BKC and Nariman Point — where reverse-charge liability, place-of-supply questions on cross-border services and exempt-supply ITC reversal are the recurring issues, not invoice volume. Trading and wholesale businesses in markets such as Kalbadevi, Masjid Bunder and Crawford Market, where high invoice counts make monthly reconciliation the core of the engagement. Import-export businesses routing goods through Jawaharlal Nehru Port and Mumbai Port, where zero-rated supplies, Letter of Undertaking exports and IGST refunds need careful documentation. The jewellery and diamond trade around Zaveri Bazaar and the Bharat Diamond Bourse, where the special 3% and 0.25% rate categories and job-work movements add their own compliance layer. And startups and media/content businesses across the Mumbai Metropolitan Region, for whom GST is often bundled with broader bookkeeping or Virtual CFO support so compliance becomes a by-product of well-kept books rather than a stand-alone monthly scramble.

CA Murli Chandak’s practice is based in Ahmedabad, and Mumbai clients are served entirely through the same digital process used across the rest of the practice — document collection, reconciliation, filing and notice replies all run online, with calls and screen-shares standing in for an in-person office visit. For a compliance function that lives on the GST portal rather than on paper, that has not been a limitation for existing Mumbai clients, and it keeps the monthly cycle identical regardless of where a business is registered.

10. Fees and How an Engagement Starts

There is no single market rate for GST work, and quotations that look comparable rarely are. The professional fee depends on invoice and transaction volumes, the number of GSTINs, the scheme (regular, QRMP or composition), whether bookkeeping is included or the client’s team maintains the books, the depth of monthly reconciliation, e-invoicing and e-way bill involvement, and whether annual returns are covered. Notice and proceeding work is scoped separately, because a registration clarification and a show-cause notice are different assignments.

CA Murli Chandak follows a scope-first approach: a free 30-minute consultation to understand the business, followed by a written quotation that states exactly which returns are covered, whether GSTR-2B/IMS reconciliation and annual returns are included, how notices are billed, and what the client’s team is expected to provide each month. Clients retain control of their own GST portal credentials and receive filing acknowledgements and reconciliation working papers for every period.

11. Why Work With CA Murli Chandak

CA Murli Chandak is a Fellow Chartered Accountant (FCA) with 8+ years in practice, based in Ahmedabad. His grounding is in audit and assurance — earlier a Partner at an Ahmedabad CA firm handling bank statutory and concurrent audits and due diligence — which is exactly the discipline GST compliance now demands: reconciliations documented, positions supported, working papers retained. Alongside compliance, he is an IBBI-Registered Valuer (Securities or Financial Assets) with 300+ valuations completed across 7+ countries including the USA, so Mumbai businesses that go on to raise funds, restructure or transact get valuation and compliance support from one advisor rather than a relay of specialists. A fuller professional background is set out separately.

What clients get, concretely: a fixed monthly cycle instead of ad-hoc filing; reconciliation before submission, not after a notice; direct access to the professional handling the work; and honest advice on scheme selection, ITC positions and notice strategy — including when a position is not worth taking.

12. Frequently Asked Questions

Who needs GST registration in Mumbai?
Registration is required once aggregate turnover crosses Rs 40 lakh (goods) or Rs 20 lakh (services), and irrespective of turnover in the compulsory categories under Section 24 — including inter-State taxable supplies of goods, casual taxable persons, reverse-charge liability and most supplies through e-commerce operators. The correct answer depends on the nature of supplies, so it is worth a specific assessment rather than a threshold rule of thumb.

Which GST returns will my business have to file?
A regular monthly filer files GSTR-1 and GSTR-3B each month. Businesses up to Rs 5 crore turnover can opt for QRMP — quarterly returns with monthly tax payment, due on the 22nd for Maharashtra-registered taxpayers. Composition taxpayers file CMP-08 quarterly and GSTR-4 annually. Annual GSTR-9 applies above Rs 2 crore and GSTR-9C above Rs 5 crore.

What is GSTR-2B and why does reconciliation against it matter?
GSTR-2B is the monthly statement of ITC generated on the 14th from your suppliers’ filings, as acted upon in the IMS. Because your credit effectively depends on it, matching your purchase register to GSTR-2B every month — and chasing suppliers on gaps immediately — is the single most valuable GST discipline a business can adopt.

Can I still edit GSTR-3B before filing?
No. From the July 2025 tax period the auto-populated liability is locked. Corrections to outward supplies go through Form GSTR-1A before GSTR-3B, or through the next period’s GSTR-1/IFF.

What is the Invoice Management System?
IMS is the GST portal dashboard where you accept, reject or keep pending the invoices and credit notes your suppliers report. Only accepted or deemed-accepted documents flow into GSTR-2B. From October 2025, credit notes can be kept pending for a defined period and ITC reversal on acceptance can be limited to the credit actually availed.

Is there a separate e-way bill threshold within Maharashtra?
Yes. Alongside the general Rs 50,000 threshold, Maharashtra requires an e-way bill for intra-State movement of goods above Rs 1 lakh, under a State notification in force since July 2018. It has not changed despite periodic reports of a lower threshold, so it is worth confirming current status rather than relying on hearsay.

Is e-invoicing applicable to my business?
Yes, if aggregate turnover at PAN level has exceeded Rs 5 crore in any financial year since 2017-18, for B2B supplies, exports and SEZ supplies. If AATO is Rs 10 crore or more, each document must also be reported to the IRP within 30 days of its date — the portal rejects older documents.

What happens if I ignore a GST notice?
The matter proceeds without your side of the story — typically to a demand, best-judgment assessment, or suspension/cancellation of registration, with interest and penalty accumulating. Every notice has a deadline; the correct response is to diarise it on day 1, reconcile the period in question, and reply with documentation.

Do I need to file GSTR-9 and GSTR-9C, and by when?
GSTR-9 is mandatory above Rs 2 crore aggregate turnover (the exemption below that is now permanent) and GSTR-9C applies above Rs 5 crore. For FY 2025-26, both are due by 31 December 2026, in the revised formats first applicable for FY 2024-25.

Does CA Murli Chandak handle GST work only in person, or is Mumbai served remotely?
The practice is based in Ahmedabad and Mumbai clients are served fully digitally — document collection, reconciliation, filing and notice replies all run through the same online process used across the practice, with no requirement for an in-person office visit.

Book a Free 30-Minute GST Consultation

Whether you need a first GST registration, a reliable monthly filing process, a reconciliation clean-up before the annual return, or a reply to a notice that has already arrived — the starting point is the same conversation: where your compliance stands today and what it will take to make it solid. The first 30 minutes are free, and you will leave with a clear picture either way.

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CA Murli Chandak – FCA | IBBI-Registered Valuer (Securities or Financial Assets) | IBBI/RV/07/2021/14408
Website: murlichandak.com
Phone: +91 99985 39902
Email: murlichandak@murlichandak.com

Disclaimer: This article is for general information only and does not constitute tax, legal or professional advice. GST rates, thresholds, forms, due dates and procedures change through notifications, circulars and portal advisories; the positions stated here were verified against publicly available sources as of August 2026 and should be confirmed against the latest official material before acting. Engagement terms, scope and fees are confirmed in writing before any assignment begins.