Is GST audit by CA still mandatory?

No. Mandatory CA/CMA audit under Section 35(5) removed from FY 2020-21 (Finance Act 2021). GSTR-9C is now self-certified by taxpayer for turnover > Rs 5 crore. But reconciliation work is identical - taxpayer bears direct responsibility. Professional support recommended.

What is the GSTR-9C filing threshold?

Aggregate turnover > Rs 5 crore (all taxable + exempt + export supplies under same PAN across all states). Filed per GSTIN. Even if one GSTIN has low turnover, PAN-level aggregate > Rs 5 crore = GSTR-9C required for all GSTINs.

What happens if GSTR-9/9C is filed late?

Late fee: GSTR-9: Rs 50/day ( Rs 5 Cr), capped. GSTR-9C: Rs 200/day (Rs 100 CGST + Rs 100 SGST), capped at 0.50% of turnover. Auto-computed. Late filing also increases departmental audit risk.

What is departmental audit Section 65?

Conducted by CGST/SGST officers at taxpayer's business premises. Commissioner's discretion based on risk parameters and data analytics. Verifies turnover, tax paid, refunds, ITC. Completed within 3 months (+ 6 months extension). ADT-04 audit report.

What triggers departmental audit in Mumbai?

GSTR-1 vs GSTR-3B turnover mismatch, ITC exceeding GSTR-2B, high refund claims, E-way bill discrepancies, GSTR-9/9C not filed, non-filing, industry risk parameters, investigation information. CGST Mumbai Zone uses data analytics. Patron's pre-audit health check prevents triggers.

Difference between GSTR-9 and GSTR-9C?

GSTR-9: annual return consolidating monthly data (outward, inward, ITC, tax). GSTR-9C: reconciliation of GSTR-9 with audited financials. GSTR-9 mandatory > Rs 2 crore. GSTR-9C additionally > Rs 5 crore. GSTR-9 reports filed data; GSTR-9C explains differences with books.

Can Patron help with past-year filing?

Yes. Businesses that haven't filed GSTR-9/9C for past years (FY 2017-18 onwards) can still file with late fees. Patron prepares past-year returns including old CA-certified format (FY 2017-20). Government periodically offers late fee waivers.

What is DRC-03 and when needed?

Form for voluntary tax payment when additional liability identified. In GST audit: if GSTR-9C Part V shows unreconciled differences = additional tax payable via DRC-03. Proactive payment demonstrates compliance and reduces penalty risk. Patron computes and facilitates.

Trusted by 10,000+ Businesses

GST Audit Service in Mumbai: GSTR-9, GSTR-9C Reconciliation, Departmental Audit Defence, and Compliance

Reviewed by CA and CS Team, Patron Accounting LLP ICAI & ICSI Registered| 15+ Years Experience| Last Updated: 25 March 2026 Verify Credentials →

GSTR-9: Annual return mandatory for aggregate turnover > Rs 2 crore | Consolidates all monthly returns for the FY

GSTR-9C: Self-certified reconciliation statement for turnover > Rs 5 crore | Reconciles audited financials with GSTR-9

Section 65: Departmental audit by CGST/SGST officers at business premises | 3 months (extendable by 6 months)

ITC Reconciliation: GSTR-2B vs books | Section 17(5) blocked credits | Rule 37/37A/42/43 reversals | DRC-03 additional liability

Our Mumbai office coordinates with CGST Mumbai Zone and MGST – 10,000+ businesses served with 4.9★ Google rating

Call +91 945 945 6700 Email Us WhatsApp Us

15+ YearsIndustry Experience

CA & CSCertified Experts

4.9

Based on 500+ reviews

Get Free Consultation

Talk to a CA/CS expert today

Full Name

Phone Number

City

Service Needed

Our team will get back to you shortly. No spam.

Real Stories from Real People

Hear how teams across industries use Patron to save time, cut costs, & stay in control.

Join 10,000+ Satisfied Businesses

Get your GST audit done by a CA team that performs 5-level reconciliation and identifies ITC risks before the Department does.

Talk to an Expert

10,000+Businesses ServedGST compliance and litigation support across India.

15+Years ExperienceDeep expertise in IP registration, GST & business compliance.

50,000+Documents FiledReturns, appeals, and filings handled accurately.

4.9★Client RatingTrusted by entrepreneurs, startups, and growing businesses.

ISO CertifiedProfessional standards and documented processes.

SSL SecureYour financial and business data is fully protected.

Overview What Is Who Needs Services Process Documents Challenges Fees Audit Types Benefits GSTR-9C Tables FAQs

GST Audit Service in Mumbai – Overview

📌 TL;DR - GST Audit Service Services at a Glance

GST audit covers GSTR-9 annual return (mandatory > Rs 2 crore), GSTR-9C self-certified reconciliation (> Rs 5 crore), departmental audit defence (Section 65), and special audit coordination (Section 66). Mandatory CA audit removed from FY 2020-21 (Finance Act 2021) but compliance burden shifted to self-certification and increased departmental scrutiny. GSTR-9C reconciles audited financials with GSTR-9: turnover (Part II), tax (Part III), ITC (Part IV), additional liability (Part V). Due date: 31 December. Late fee: Rs 200/day for GSTR-9C (capped 0.50% of turnover). DRC-03 for additional liability.

Mumbai businesses across every sector need GST audit support: Fort/Crawford Market traders with turnover reconciliation, Andheri MIDC manufacturers with complex ITC, BKC service companies with multi-state registrations, Powai tech firms with export/SEZ transactions, and Dadar wholesalers with inter-state supply. Learn more about GST Audit across India.

Patron Accounting's Mumbai office provides end-to-end GST audit: 5-level books-to-return reconciliation, GSTR-9 preparation, GSTR-9C reconciliation, ITC risk identification, departmental audit representation, and DRC-03 payment. For GST registration, see GST Registration in Mumbai. For returns, see GST Return Filing.

Content is reviewed quarterly for accuracy.

What Is GST Audit Service?

GST audit is the comprehensive review, reconciliation, and compliance management of GST records, returns, and financials. Three areas: (1) annual return and reconciliation (GSTR-9/9C), (2) internal GST health check (voluntary pre-audit review), and (3) departmental audit defence (Section 65/66 representation).

CA/CMA audit under Section 35(5) removed from FY 2020-21 (Finance Act 2021). GSTR-9C is now self-certified – taxpayer bears direct responsibility for accuracy. Errors trigger departmental audit, demand, or penalty. For Statutory Audit, see our page.

For Mumbai businesses with high turnover and complex transactions, a single reconciliation error can trigger departmental action. For Accounting Services, see our page.

Key Terms for GST Audit Service:

GSTR-9: Annual return – mandatory for aggregate turnover > Rs 2 crore
GSTR-9C: Self-certified reconciliation – mandatory for turnover > Rs 5 crore
Section 65: Departmental audit by CGST/SGST officers – 3 months + 6 months
Section 66: Special audit by CA/CMA nominated by Commissioner – 90 + 90 days
DRC-03: Voluntary tax payment for additional liability from reconciliation
GSTR-2B: Auto-generated inward supply statement – benchmark for ITC verification

CA Managed GST Audit

When Mumbai Businesses Need GST Audit Services

Fort/Crawford Market traders (turnover > Rs 5 crore) – High-volume with thousands of invoices, multiple HSN codes, complex credit notes. Turnover reconciliation between books, GSTR-1, and GSTR-3B is critical. Patron reconciles for Mumbai traders.

Andheri MIDC/Thane-Belapur manufacturers – Raw material ITC, capital goods ITC, job work, stock transfers, exports. ITC reconciliation (GSTR-2B vs books) is most complex area. Section 17(5) blocked credits, proportional ITC. Patron manages for Mumbai manufacturers.

BKC service companies (multi-state) – IT, consulting, financial services with multiple GSTINs. GSTR-9C filed per GSTIN. Inter-state transfers, cross-charging, shared services. Patron manages per-GSTIN reconciliation.

Powai tech firms (exports/SEZ) – Software exports under LUT, SEZ supplies (zero-rated), domestic supplies. Zero-rated reconciliation, LUT monitoring, ITC refund on exports. Patron handles export-focused GST audit.

Businesses receiving Section 65 audit notice – CGST/SGST departmental audit requires immediate professional representation. Patron represents Mumbai businesses during the entire audit. For Pvt Ltd Compliance, see our page.

Businesses with significant ITC claims – ITC as large percentage of output tax (trading/manufacturing) = higher audit risk. Department uses GSTR-2B vs GSTR-3B analysis. Patron pre-audits ITC claims for Mumbai businesses.

GST Audit Services Included

Service	What We Do
GSTR-9 Annual Return	Consolidating GSTR-1, GSTR-3B, GSTR-2B data. 19 tables across 6 parts. Outward/inward supplies, ITC availed/reversed, tax paid, prior FY adjustments. Complete data validation for Mumbai businesses
GSTR-9C Reconciliation Statement	Part II: turnover (financials vs GSTR-9). Part III: tax (books vs GSTR-9). Part IV: ITC (books vs GSTR-9 vs GSTR-2B). Part V: additional liability. Detailed variance explanations. Self-certification review
Books-to-Return Reconciliation	5 levels: Revenue GL vs GSTR-1, Purchase GL vs GSTR-2B, Output tax vs GSTR-3B, ITC vs GSTR-3B vs GSTR-2B, Financial statements vs GSTR-9. Every level reconciled for Mumbai businesses
ITC Reconciliation & Verification	GSTR-3B vs GSTR-2B vs books. Credits at risk (not in 2B), missed credits (in 2B not claimed), Section 17(5) blocked, Rule 37/37A (non-payment/non-filing), Rule 42/43 (proportional reversal)
Departmental Audit Defence (S65)	Prepare records, accompany audit team at Mumbai premises, respond to observations in writing, manage audit conclusion. Full representation for CGST Mumbai Zone and MGST audits
Special Audit Coordination (S66)	Coordinate with nominated CA/CMA, provide records, manage process, respond to findings. For complex cases during scrutiny/investigation
DRC-03 Additional Liability	If GSTR-9C Part V shows unreconciled differences: compute additional tax + interest. Pay via DRC-03 before Department initiates demand. Proactive compliance for Mumbai businesses
Pre-Audit Health Check	Voluntary internal review before filing deadline: HSN reconciliation, E-way bill compliance, reverse charge, composition dealer compliance, threshold monitoring. Identifies and corrects errors proactively

Our Process

GST Audit Process in Mumbai

Patron starts preparation in October (3 months before deadline), completes reconciliation by November, and files in early December. For departmental audits: preparation begins on day one of notice.

Step 1

Data Collection & Turnover Reconciliation

Gather trial balance (GSTIN-wise), sales/purchase registers, GSTR-1/3B/2B summaries (12 months), financials. 3-way turnover reconciliation: books vs GSTR-1 vs GSTR-3B. Identify unbilled revenue, advances, credit notes, non-GST income, exempt supplies. Patron performs complete data collection and reconciliation for Mumbai businesses.

Data collectedTurnover reconciled

Reconciled01

Step 2

ITC & Tax Reconciliation

ITC per books vs GSTR-3B vs GSTR-2B: identify credits at risk (not in 2B), missed credits (in 2B not claimed), Section 17(5) blocked, Rule 37/37A/42/43 reversals. Output tax per books vs GSTR-3B/GSTR-1: rate changes, place of supply, RCM. Patron performs comprehensive ITC and tax reconciliation for Mumbai businesses.

ITC reconciledTax matched

Verified02

Step 3

GSTR-9 & GSTR-9C Preparation

GSTR-9: 19 tables across 6 parts with validated data. GSTR-9C: Part II (turnover), Part III (tax), Part IV (ITC), Part V (additional liability). Detailed variance explanations for every difference. Self-certification review before taxpayer signs. Patron prepares both forms for Mumbai businesses with complete accuracy.

GSTR-9 preparedGSTR-9C reconciled

Prepared03

Step 4

DRC-03, Filing & Audit Defence

If unreconciled differences: compute and pay additional tax via DRC-03. File GSTR-9 + GSTR-9C on GST portal. Verify status. For departmental audit (Section 65): prepare records, accompany audit team, respond to observations. Patron manages filing and represents Mumbai businesses during audits.

Filed on timeAudit-ready

Complete04

Documents Required for GST Audit

Trial Balance: GSTIN-wise, rate-wise breakup of all taxable supplies
Audited Financial Statements: P&L, Balance Sheet, audit report
GSTR-1 Monthly Summaries: All 12 months (April to March)
GSTR-3B Monthly Summaries: All 12 months
GSTR-2B Monthly Summaries: All 12 months (auto-generated)
Sales & Purchase Registers: Taxable, exempt, nil-rated, export, RCM
Debit/Credit Note Register: All issued and received during the year
HSN Summaries: Outward and inward supply HSN-wise breakup
E-way Bill Register: All E-way bills generated (for S65 audit)
ITC Reversal Workings: Rule 37 (180-day), Rule 37A, Rule 42/43

Mumbai-Specific Tip: Mumbai businesses with multiple verticals under a single GSTIN must ensure all supplies are captured under correct HSN/SAC codes. CGST Mumbai Zone increasingly scrutinises HSN-level data in GSTR-9 against auto-populated GSTR-1 summary. Any mismatch triggers departmental audit queries. Patron validates HSN-level data before filing.

Common Challenges in GST Audit for Mumbai Businesses

Challenge	Impact	How Patron Accounting Solves It
Turnover Reconciliation Differences	Financials don't match GSTR-1/GSTR-3B: unbilled revenue, advances (GST on service advances), credit notes, non-GST income (interest, dividend), exempt supplies, inter-state stock transfers	3-way reconciliation: books vs GSTR-1 vs GSTR-3B. Every difference identified and explained in GSTR-9C Part II with valid reasons for Mumbai businesses
ITC Mismatch (GSTR-2B vs Books)	ITC claimed doesn't match GSTR-2B: supplier filed late, wrong details, March purchases in April 2B, ITC on invoices not yet in 2B. Department uses 2B as benchmark	GSTR-2B vs books reconciliation. At-risk credits flagged. Proactive reversal + reclaim strategy. Patron identifies risk for Mumbai businesses
Ineligible ITC Section 17(5)	ITC claimed on blocked items: motor vehicles, food/beverages, club membership, personal consumption, works contract (except for further supply)	Section 17(5) compliance review. Ineligible credits identified and reversed. GSTR-9C flags differences. Patron reviews for Mumbai businesses
Multi-GSTIN Reconciliation	Companies with multiple state registrations: GSTR-9C per GSTIN but PAN-level turnover determines applicability. Inter-unit transactions (stock transfers, cross-charges) complex	Per-GSTIN reconciliation with inter-unit transaction mapping. Patron manages for BKC multi-state companies
Departmental Audit Preparedness	Records disorganised. Reconciliations not done. Prior year differences unaddressed. 3-month audit window requires immediate preparation	Audit-readiness preparation on notice receipt. Records organised, reconciliations completed, prior issues addressed. Patron prepares Mumbai businesses

GST Audit Service Fees in Mumbai

Fee Component	Amount
GSTR-9C Late Fee	Rs 200/day (Rs 100 CGST + Rs 100 SGST) – capped at 0.50% of turnover
GSTR-9 Late Fee	Rs 50/day (≤ Rs 5 Cr) / Rs 100/day (> Rs 5 Cr) – capped at % of turnover
General Penalty (Non-Compliance)	Rs 25,000 (Section 125) – failure to maintain records or cooperate with audit
Patron Fee – GSTR-9 Only (Rs 2-5 Cr)	Starting Rs 10,000 per GSTIN (annual return + validation + filing)
Patron Fee – GSTR-9 + 9C (> Rs 5 Cr)	Starting Rs 25,000 per GSTIN (annual return + reconciliation + self-certification + filing)
Patron Fee – Multi-GSTIN Package	Starting Rs 20,000 per additional GSTIN
Patron Fee – Pre-Audit Health Check	Starting Rs 15,000 per GSTIN (voluntary internal review)
Patron Fee – Departmental Audit Defence (S65)	Starting Rs 25,000 (preparation + representation + observation response)
Patron Fee – ITC Reconciliation Only	Starting Rs 10,000 per GSTIN (GSTR-2B vs books + Rule verification)
Patron Fee – DRC-03 Computation + Payment	Starting Rs 5,000 (liability computation + payment facilitation)

All fees and charges listed are indicative only and do not constitute a binding offer. Final amounts may vary depending on the volume of work and the complexity involved.

Professional service charges for drafting, filing, and representation are separate from the statutory fees. The exact fee depends on the complexity of the case, disputed amount, and number of hearings required. Contact us for a detailed quote.

Get a free GST Audit Service consultation - Call +91 945 945 6700 or WhatsApp us. No-obligation assessment.

Types of GST Audit – Comparison

Stage	Estimated Timeline
Annual Reconciliation (GSTR-9C)	Aggregate turnover > Rs 5 crore \| Self-certified \| Reconcile financials with returns \| By 31 December
Departmental Audit (Section 65)	Commissioner discretion; risk parameters \| CGST/SGST officers at premises \| 3 months + 6 months extension
Special Audit (Section 66)	During scrutiny/investigation; value/ITC appears inaccurate \| CA/CMA nominated \| 90 + 90 days
Old CA/CMA Audit (Section 35(5))	Was turnover > Rs 2 crore \| REMOVED from FY 2020-21 \| Applies to prior FY only

With mandatory CA audit removed, CGST Mumbai Zone has significantly increased departmental audits under Section 65. Mumbai businesses that previously had CA-certified GSTR-9C now bear direct self-certification responsibility. The Department's data analytics flags GSTR-1 vs GSTR-3B mismatches, ITC anomalies, and E-way bill discrepancies automatically. Patron's proactive GST audit ensures Mumbai businesses are audit-ready before the Department comes calling.

Key Benefits

Why Choose Patron for GST Audit in Mumbai

CGST & MGST Coordination

Centrally located for CGST Mumbai Zone (multiple Commissionerates) and MGST coordination. For simultaneous CGST and MGST proceedings: managed from single point.

5-Level Reconciliation

Revenue GL vs GSTR-1, Purchase GL vs GSTR-2B, Output tax vs GSTR-3B, ITC vs GSTR-3B vs GSTR-2B, Financials vs GSTR-9. No shortcut – every level reconciled for Mumbai businesses.

ITC Risk Identification

Credits at risk of denial (not in 2B), credits requiring reversal (S17(5)/Rule 37/42/43), and missed credits (in 2B not claimed). Prevents both demand and missed recovery for Mumbai businesses.

Self-Certification Review

Independent review before taxpayer self-certifies GSTR-9C. Every difference explained, additional liability computed, DRC-03 facilitated. Converts self-certification from risk to strength.

Trusted by Mumbai Businesses for GST Audit

Trust Signals: 10,000+ Businesses | 4.9 Google Rating | 50,000+ Documents Filed | 15+ Years

“Patron identified Rs 12 lakh of ITC we had claimed but was not in GSTR-2B – all from one supplier who had not filed returns. They helped us reverse proactively in GSTR-9C and pay via DRC-03 before the Department noticed. Six months later, the supplier filed and we reclaimed the credit.”

— Director, Manufacturing Company, Andheri MIDC

Offices in Pune, Mumbai, Delhi, and Gurugram serving businesses with GST audit, annual return, and compliance.

GSTR-9C Reconciliation – Key Tables

Part	What It Reconciles	Common Mumbai Differences
Part II: Turnover (Tables 5A-5Q)	Gross/taxable turnover per financials vs GSTR-9	Unbilled revenue, advances, credit notes, non-GST income, exempt supplies
Part III: Tax (Tables 9A-9Q)	Tax paid per books vs GSTR-9	Rate differences, place of supply errors, RCM timing, credit note tax
Part IV: ITC (Tables 12A-12C)	ITC per books vs GSTR-9 vs GSTR-2B	GSTR-2B mismatch, blocked credit not reversed, Rule 37/37A, missed credits
Part V: Additional Liability (Tables 14-16)	Additional tax from unreconciled differences	Sum of all unreconciled differences from Parts II-IV; payable via DRC-03

Related Services

Explore related services:

Legal & Compliance Framework

Section 35(5): Mandatory CA/CMA audit – REMOVED from FY 2020-21 (Finance Act 2021)
Section 44: Annual return (GSTR-9) + reconciliation (GSTR-9C)
GSTR-9: Mandatory for aggregate turnover > Rs 2 crore; due 31 December
GSTR-9C: Self-certified for turnover > Rs 5 crore; due 31 December
Section 65: Departmental audit – 3 months + 6 months extension
Section 66: Special audit – 90 + 90 days
Section 17(5): Blocked ITC (motor vehicles, food, clubs, personal)
Rule 37/37A: ITC reversal for non-payment to supplier / supplier non-filing
Rule 42/43: Proportional ITC reversal for exempt supplies
DRC-03: Voluntary tax payment for additional liability
CGST Mumbai Zone: Mumbai Central, South, East, Thane Commissionerates

Filing Portal: cbic.gov.in | gst.gov.in

Frequently Asked Questions – GST Audit Service in Mumbai

Get answers about CA audit requirement, GSTR-9C threshold, late fees, departmental audit, triggers, GSTR-9 vs GSTR-9C, past-year filing, and DRC-03 for Mumbai businesses.

Quick Answers

GST audit karna zaroori hai kya? CA/CMA audit hata diya gaya hai FY 2020-21 se. Lekin GSTR-9 mandatory hai (> Rs 2 Cr) aur GSTR-9C self-certified mandatory hai (> Rs 5 Cr). Departmental audit kabhi bhi aa sakta hai. Professional support zaroori hai kyunki self-certification mein galti = Department action.

GSTR-9C mein kya reconcile karna hota hai? Part II: turnover (financials vs returns). Part III: tax (books vs returns). Part IV: ITC (books vs returns vs GSTR-2B). Part V: additional liability. Har difference ka reason dena padta hai. Patron har level reconcile karta hai.

Section 65 audit ka notice aaya hai? Records organise karo. Reconciliation pehle se kar lo. Audit team ko premises pe access do. Written response do observations pe. Patron audit ke dauran represent karta hai aur observations ka response draft karta hai.

Don't Let Self-Certification Become Self-Liability – Get Professional GST Audit

With mandatory CA audit removed, you bear direct responsibility for GSTR-9C accuracy. The CGST Mumbai Zone has increased departmental audits to fill the verification gap. A single reconciliation error can trigger a departmental audit, demand notice, or penalty. The 31 December filing deadline is firm – late fee accrues at Rs 200/day.

Get your GST audit started today – Call +91 945 945 6700 or WhatsApp us.

Get End-to-End GST Audit Service in Mumbai

GST audit in Mumbai covers GSTR-9 annual return, GSTR-9C self-certified reconciliation, departmental audit defence, special audit coordination, ITC reconciliation, and DRC-03 additional liability payment. With mandatory CA audit removed, professional support is more critical than ever for accurate self-certification.

Patron Accounting's Mumbai office provides 5-level reconciliation, GSTR-9/9C preparation with detailed variance explanations, ITC risk identification, departmental audit representation before CGST Mumbai Zone and MGST, and proactive compliance management for traders, manufacturers, service companies, and technology firms across Mumbai.

With offices in Pune, Mumbai, Delhi, and Gurugram, 10,000+ businesses served, and 4.9 Google rating, Patron Accounting LLP delivers expert GST audit services across India.

📞 Call +91 945 945 6700 💬 WhatsApp Us ✉️ Email Us

Book a Free Consultation - No Obligation.

GST Audit Service Across India

Patron Accounting handles GST audit in major cities with 5-level reconciliation, ITC risk identification, and departmental audit defence.

GST Audit Service in Other Cities

Professional GST audit across India

Pune

Maharashtra

Mumbai

Maharashtra

You're here

Related Services in Mumbai

End-to-end business compliance

Trademark Registration

Mumbai

Payroll Services

Mumbai

Content Created: 25 March 2026 | Last Updated: 25 March 2026 | Next Review: 25 June 2026 | Reviewed By: CA & CS Team, Patron Accounting LLP

This content is reviewed quarterly for CGST Act amendments, GSTR-9/9C format changes, notification updates, and departmental audit trends. Freshness Tier: 1.