GST Filing Mumbai: 2026 Deadlines, Costs, And Costly Mistakes

Key Takeaways

• Registration Threshold: GST registration is mandatory for Mumbai businesses with aggregate turnover above ₹40 lakh for goods or ₹20 lakh for services under Section 22 of the CGST Act, 2017
• Core Returns: Most Mumbai businesses file GSTR-1 for outward supplies and GSTR-3B for summary and payment, either monthly or quarterly under the QRMP scheme
• Monthly Filing Due Dates: GSTR-1 by the 11th, GSTR-3B by the 20th of the following month
• Quarterly Filing Due Dates (QRMP): GSTR-1 by the 13th, GSTR-3B by the 22nd of the month after quarter end, Maharashtra is a Category 1 state
• Late Fee: ₹50 per day per return, ₹20 per day for nil returns, capped at ₹10,000 per return under Section 47
• Interest On Unpaid Tax: 18% per annum from the due date to the date of actual payment under Section 50
• GSTIN Suspension: Triggered automatically after 6 consecutive months of non-filing for monthly filers or 2 consecutive quarters for QRMP filers
• ITC Matching: Input Tax Credit is claimable only on invoices appearing in GSTR-2B, generated on the 14th of each month, provisional ITC is no longer permitted
• Typical Filing Charges In Mumbai: ₹1,000 to ₹2,500 per month for small businesses, ₹3,000 to ₹6,000 per month for mid-size, ₹8,000 to ₹20,000+ per month for exporters and e-commerce sellers

GST Filing In Mumbai: Overview

If your Mumbai business is registered for GST, filing is not optional and it is not forgiving. GST filing in Mumbai follows the same national framework, but the city’s commercial reality adds layers: inter-state sales attract IGST, intra-state Maharashtra transactions split into CGST and SGST, and the density of trading activity means the department watches ITC mismatches closely.

The basics are straightforward, file on time, pay what you owe, claim only what you can support. The details are where most businesses lose money or attract notices. This guide covers every return type, every deadline, the charges you should expect to pay, how ITC reconciliation works, what happens when things go wrong, and how to pick the right person to handle it. If you want your filings managed rather than learning all of this yourself, Virtual Accounting by AI Accountant handles end-to-end GST compliance starting at ₹4,000 per month.

Which GST Returns Apply To Your Mumbai Business

Not every business files the same returns. The forms you need depend on your turnover, your registration type, and what kind of transactions you run.

GSTR-1 covers outward supplies, every sale you make. If your aggregate turnover is above ₹5 crore, you file monthly by the 11th of the following month. If you are under ₹5 crore and opted into the QRMP scheme, you file quarterly by the 13th of the month after the quarter ends. QRMP filers can also upload B2B invoices in months one and two of the quarter through the Invoice Furnishing Facility (IFF), due by the 13th of that same month.

GSTR-3B is the summary return where you declare your total tax liability and pay it. Monthly filers submit by the 20th. QRMP filers in Maharashtra, state code 27, submit by the 22nd of the month after the quarter ends.

GSTR-9 is the annual return filed by all regular taxpayers with aggregate turnover above ₹2 crore. It is due by 31 December of the following financial year. If your turnover exceeds ₹5 crore, you also file GSTR-9C, a self-certified reconciliation statement between your audited books and your GST returns, also due 31 December and requiring a Chartered Accountant or Cost Accountant sign-off.

Composition dealers, turnover up to ₹1.5 crore under the simplified scheme, file CMP-08, a quarterly challan-cum-statement, due by the 18th of the month after each quarter. They also file GSTR-4, the annual return, by 30 April each year.

E-commerce operators running their own platforms, not sellers on marketplaces, file GSTR-8 for TCS collected, due by the 10th of the following month. Businesses making payments under TDS provisions file GSTR-7, also by the 10th.

Mumbai has a high proportion of service exporters, e-commerce sellers, and professional consultants. Each has a different return mix. Get clear on which forms apply before you build your compliance calendar.

GST Filing Due Dates And Deadlines For Mumbai Businesses

Here is the complete filing calendar for the most common return types:

For monthly GST filing in Mumbai, the two dates that matter most are the 11th for GSTR-1 and the 20th for GSTR-3B. Build your internal accounting cut-off around those.

Late fee under Section 47 of the CGST Act: ₹50 per day per return for returns with tax liability, ₹25 CGST and ₹25 SGST, capped at ₹10,000 per return. For nil returns, it is ₹20 per day, ₹10 and ₹10, capped at ₹2,000 under recent CBIC notifications. Interest on unpaid tax runs at 18% per annum from the due date until actual payment under Section 50. See the official GSTR-3B user guide at tutorial.gst.gov.in.

If you want to switch between monthly and QRMP filing, the opt-in or opt-out deadline is the 31st of the first month of the quarter, for example, 31 October to opt in for the October to December quarter.

The GST portal sends email and SMS reminders, but treat those as unreliable. Maintain your own compliance calendar and set internal reminders three to four days before each deadline to allow for data preparation and any portal issues.

Step By Step GST Return Filing Process On The GST Portal

You file at www.gst.gov.in. Login with your GSTIN and password, authenticate via DSC for companies and LLPs or EVC for proprietors and partnerships.

Filing GSTR-1:

Navigate to Services → Returns → Returns Dashboard → select the financial year and return period → choose GSTR-1.

• Table 4A: B2B invoices with the buyer’s GSTIN
• Table 5: B2C large invoices above ₹2.5 lakh, unregistered buyers, inter-state
• Table 7: B2C small invoices, aggregate, state wise
• Table 6: Exports with or without payment of IGST
• Tables 9 and 10: Credit and debit notes
• Table 11: Advances received on which tax is payable

Filing GSTR-3B:

GSTR-3B is partially auto populated from GSTR-1. You confirm outward tax liability, declare ITC claimed, only what appears in GSTR-2B, compute net tax payable, and pay via the Electronic Cash Ledger or offset using the Electronic Credit Ledger.

What You Need Before You File:

• Sales register with correct HSN or SAC codes for every line item
• Purchase invoices for ITC claims
• Bank confirmation that all outward invoices are against actual supply
• TDS or TCS certificates where applicable

HSN Or SAC Reporting Rules: Turnover above ₹5 crore requires 6 digit HSN on every invoice. Between ₹1.5 crore and ₹5 crore, 4 digit HSN is sufficient. Below ₹1.5 crore it is optional, but good practice.

Nil Return Shortcut: If you have zero outward supplies for the period, file a nil GSTR-3B via SMS. See the steps in this nil return guide. Send NIL 3B [GSTIN] [Tax Period] to 14409 from your registered mobile number.

Common Errors That Trigger Notices: wrong GSTIN on a supplier invoice, ITC claimed on blocked credit categories under Section 17(5), mismatch between the tax liability declared in GSTR-1 versus GSTR-3B. That last one is the most common trigger for a scrutiny notice in Maharashtra.

GST Filing Charges In Mumbai — What You Should Actually Pay

Pricing for GST filing in Mumbai is determined by complexity, not just by turnover. Any consultant who quotes based on turnover alone is using the wrong metric.

Typical Market Rates For GST Filing Charges In Mumbai, FY 2026:

• Nil return filing: ₹200 to ₹500 per return
• Small business, under 50 invoices per month, GSTR-1 and GSTR-3B only: ₹1,000 to ₹2,500 per month
• Mid size business, 50 to 200 invoices, GSTR-1 and GSTR-3B and GSTR-2B reconciliation: ₹3,000 to ₹6,000 per month
• Complex filing, exporter with LUT, e-commerce seller, multiple GSTINs, high credit or debit note volume: ₹8,000 to ₹20,000+ per month
• Annual return, GSTR-9 and GSTR-9C: ₹5,000 to ₹25,000 one time depending on turnover and complexity

What drives the price up: multiple GSTINs across states, inter-state and export transactions, LUT filing and refund claims, e-commerce aggregator TCS reconciliation, a large backlog of unfiled or incorrectly filed prior periods, and high volumes of debit or credit note adjustments.

What the monthly fee should include as standard: data compilation support, GSTR-1 filing, GSTR-3B filing, GSTR-2B reconciliation, payment challan generation, and handling routine portal queries. Get this in writing as a scope of work document before you sign anything.

For a benchmark, Virtual Accounting by AI Accountant offers a bundled plan starting at ₹4,000 per month that covers GST filing plus bookkeeping up to 200 transactions, useful if you want both handled under one engagement rather than coordinating between a separate bookkeeper and a GST consultant.

Input Tax Credit Reconciliation — Where Mumbai Businesses Lose Money

Input Tax Credit, ITC, lets you offset GST paid on purchases against GST collected on sales. In practice, this is where most Mumbai businesses either recover significant cash or unknowingly lose it.

The rule since January 2022: Under Section 16(2)(aa) of the CGST Act, ITC is restricted to what appears in your GSTR-2B. That is a static auto populated statement generated on the 14th of each month, reflecting invoices your suppliers uploaded to GSTR-1 in the prior period. If a supplier did not file their GSTR-1, their invoices do not appear in your GSTR-2B and you cannot claim ITC on them, regardless of whether you have the physical invoice and have made the payment. See a plain language explainer at patronaccounting.com.

Rule 36(4) killed provisional ITC. There is no longer any buffer. It is 100% GSTR-2B matching or no ITC.

Practical consequence: a Mumbai trading business dealing with 30 to 40 small suppliers, some of whom file quarterly or irregularly, can lose ₹20,000 to ₹50,000 per month in ITC simply because of supplier non-compliance. The solution is a monthly reconciliation: match your purchase register against GSTR-2B, identify missing invoices, and follow up with those vendors before their GSTR-1 deadline.

GSTR-2B vs GSTR-2A: GSTR-2A is dynamic, real time. GSTR-2B is static and legally definitive. For ITC purposes, GSTR-2B is the only document that matters.

Blocked credits under Section 17(5), no ITC regardless of supplier compliance:

• Motor vehicles, except for specific eligible businesses
• Food and beverages, outdoor catering
• Beauty treatment, health services, fitness centre memberships
• Club memberships, rent a cab
• Life and health insurance, unless it is a statutory obligation
• Works contract services for construction or renovation of immovable property

ITC reversal under Rule 37: If you claimed ITC on an invoice but have not paid the supplier within 180 days of the invoice date, you must reverse that ITC and pay interest at 18% per annum. Once you make the payment, you can re claim the credit.

Penalties, Notices, And Consequences Of Non-Compliance In Mumbai

Missing a GST filing is not a minor administrative oversight. The consequences stack fast and the Maharashtra GST department is active in issuing scrutiny notices. Learn more in this explainer on the real cost of GST non compliance.

Late fee under Section 47: ₹50 per day per return for returns with tax liability, capped at ₹10,000. For nil returns, ₹20 per day capped at ₹2,000. This applies per return, so if you miss three months of GSTR-3B, you can pay up to ₹30,000 in late fees before interest.

Interest under Section 50: 18% per annum on unpaid or short paid tax from the original due date to actual payment. On excess ITC wrongly claimed and utilised, the rate is 24% per annum.

GSTIN suspension under Rule 21A: if a monthly filer misses returns for 6 consecutive months, or a QRMP filer misses returns for 2 consecutive quarters, the GSTIN is automatically suspended. A suspended GSTIN means you cannot issue valid tax invoices and customers will not be able to claim ITC, so they will stop buying until you are reinstated.

Revocation after cancellation: file all pending returns, pay all dues, and apply for revocation within 90 days of the cancellation order.

Scrutiny notice under Section 61: discrepancies between GSTR-3B and GSTR-1 or GSTR-2B can trigger a notice. You have 30 days to respond. Ignoring it can convert the scrutiny into a demand order.

Demand under Section 73, non fraud cases: tax plus interest plus penalty up to 10% of tax, minimum ₹10,000. Section 74, fraud or wilful suppression: tax plus interest plus penalty up to 100% of tax.

E-way bill non-compliance: for goods in transit without a valid e-way bill, the penalty is the higher of ₹10,000 or the tax amount on those goods.

Respond to every notice within the stated deadline. A clarification notice that is ignored escalates to a demand order, which is significantly harder and more expensive to contest.

How To Choose A GST Consultant Or Filing Service In Mumbai

GST return filing can legally be done by a Chartered Accountant, a Cost Accountant, a Company Secretary, a GST Practitioner enrolled under Rule 83, or by the business owner or authorised signatory.

The practical distinction: a GSTP can file returns on your behalf but cannot sign GSTR-9C. That reconciliation statement requires a CA or Cost Accountant. If your turnover is above ₹5 crore and you hire a non CA for annual compliance, you will hit a wall at the GSTR-9C stage.

Questions to ask before you engage:

1. Do you file on our GSTIN using an authorised signatory login, or do you use a shared or own login?
2. Who is responsible if a return is filed late due to your error, and how is that handled?
3. Is GSTR-2B reconciliation included in the monthly fee or billed separately?
4. Do you handle GST notices and departmental correspondence, and is that in scope or extra?
5. Are you a GSTP enrolled individual or a CA firm, and is CA sign off available for GSTR-9C if we cross ₹5 crore?

Red flags: requests for your portal credentials instead of adding themselves as authorised signatory, no written engagement letter or scope, vague deliverables, and no clear escalation contact.

GST Filing For Specific Business Types Common In Mumbai

Exporters (JNPT And Nhava Sheva Proximity)

If you export goods or services, file a Letter of Undertaking, LUT under Form RFD-11 on the GST portal before the first export of each financial year. An LUT lets you export without paying IGST upfront. If you miss filing the LUT and pay IGST on exports, you can claim a refund through GSTR-1, shipping bill route, or Form RFD-01. Refunds are supposed to be processed within 60 days of acknowledgement, after which 6% per annum interest applies under Section 56.

E-Commerce Sellers (Amazon, Flipkart, Meesho)

If you sell on an e-commerce aggregator platform, GST registration is mandatory regardless of your turnover under Section 24(ix) of the CGST Act. The platform deducts TCS at 1% of net taxable sales, 0.5% CGST and 0.5% SGST or IGST. This appears in the operator’s GSTR-8 and auto reflects in your GSTR-2B. You claim it back in GSTR-3B as a credit against your output liability.

Restaurants And F&B

Under the composition scheme, you pay 5% GST on turnover with no ITC, file CMP-08 quarterly, and GSTR-4 annually. As a regular taxpayer, you typically pay 5% GST on food and non alcoholic beverages with no ITC, or 18% GST with ITC under specific conditions like air conditioned premises or liquor licence. If orders come through food aggregators, they collect and deposit the GST on those orders, and you reflect nil for those supplies in GSTR-3B.

Real Estate And Developers

Under construction residential property attracts 5% GST, or 1% for affordable housing, with no ITC. Once the Occupancy Certificate is received, the property sale is exempt from GST. Works contract services for construction attract 12% or 18% GST depending on the contract, with ITC available in the B2B chain.

Professionals And Consultants

Standard rate for professional services is 18% GST. Watch Reverse Charge Mechanism rules: imports of services fall under RCM, and certain domestic procurements from unregistered vendors may be subject to RCM based on notifications.

Get Your GST Filing Handled Without Building An In-House Team

If you want this off your plate, Virtual Accounting by AI Accountant offers a done for you GST filing service for Mumbai founders and finance leads. A dedicated CA team handles GSTR-1, GSTR-3B, GSTR-2B reconciliation, and annual compliance, with bookkeeping included. Pricing starts at ₹4,000 per month up to 200 transactions. One engagement, one point of contact, handled. Details

Frequently Asked Questions: GST Filing Mumbai

What Is The Turnover Threshold For Mandatory GST Registration In Mumbai?

For businesses supplying goods, the threshold is ₹40 lakh aggregate annual turnover. For service providers, it is ₹20 lakh. Mumbai is not a special category state, so these standard thresholds apply. Certain categories such as e-commerce sellers and inter-state suppliers must register regardless of turnover under Section 24.

What Is The Difference Between GSTR-1 And GSTR-3B?

GSTR-1 is the detailed outward supply return that lists every invoice you issued. GSTR-3B is the monthly or quarterly summary where you declare total output tax, claim eligible ITC from GSTR-2B, and pay net tax. Most regular taxpayers must file both on the same monthly or QRMP cadence.

What Happens If I File GSTR-3B Late In Mumbai?

A late fee of ₹50 per day, ₹25 CGST and ₹25 SGST, applies for returns with tax liability, capped at ₹10,000 per return. For nil returns, ₹20 per day capped at ₹2,000. Separately, 18% per annum interest accrues on any unpaid tax from the original due date until actual payment.

Can I Claim ITC If My Supplier Has Not Filed Their GSTR-1?

No. Since January 2022, ITC is restricted to invoices that appear in your GSTR-2B. If a supplier’s invoice is missing in 2B, you cannot claim credit on it even if you have the invoice and have paid for it. Follow up with non compliant vendors before their GSTR-1 due date so their invoices flow into your next 2B.

What Is The QRMP Scheme And Is It Right For My Mumbai Business?

The Quarterly Return Monthly Payment scheme allows businesses with turnover up to ₹5 crore to file GSTR-1 and GSTR-3B quarterly while paying tax monthly. It reduces the number of returns from 24 to 8 annually, but requires timely monthly payments to avoid interest. In Maharashtra, QRMP GSTR-3B is due on the 22nd of the month after quarter end.

Do I Need A CA To File GST Returns, Or Can My Team Handle It?

A CA, Cost Accountant, Company Secretary, enrolled GST Practitioner, or the business owner can file routine returns. However, GSTR-9C for turnover above ₹5 crore must be certified by a CA or Cost Accountant. If you want an end to end managed option with CA oversight, consider Virtual Accounting by AI Accountant for routine filings plus annual compliance.

What Filing Charges Should I Budget For In Mumbai?

As a working range: ₹1,000 to ₹2,500 per month for small businesses under 50 invoices, ₹3,000 to ₹6,000 per month for mid sized businesses that include GSTR-2B reconciliation, and ₹8,000 to ₹20,000+ per month for complex cases such as exporters, e-commerce sellers, or multiple GSTINs. Annual returns including GSTR-9C typically run ₹5,000 to ₹25,000 one time depending on complexity.

My GSTIN Has Been Suspended. How Do I Get It Restored?

Immediately file all pending returns, pay the outstanding tax, interest, and late fees, then apply online for revocation of suspension or cancellation. If your registration was cancelled, the revocation application must be filed within 90 days of the cancellation order. If you prefer expert handling, Virtual Accounting by AI Accountant can manage the catch up filings and revocation process end to end.

I Am An Exporter In Mumbai. Do I Need To Pay GST On Exports?

No, provided you file an LUT, Form RFD-11, before your first export of each financial year. Under an LUT, you can export without payment of IGST. If IGST is already paid on exports, you can claim a refund through the shipping bill route in GSTR-1 or by filing Form RFD-01, with interest at 6% if processing exceeds 60 days from acknowledgement.

What Is The Difference Between GSTR-2B And GSTR-2A, And Which One Matters For ITC?

GSTR-2B is a static statement generated on the 14th of each month that locks in the invoices eligible for ITC. GSTR-2A is dynamic and updates as suppliers file or amend returns. For claiming ITC under Section 16(2)(aa), only GSTR-2B has legal weight.

How Do I Switch Between Monthly And QRMP Filing And By When?

You can opt in or out of QRMP on the GST portal. The cut off is the 31st of the first month of the quarter, for example, 31 January for Q4. Plan the switch around your cash flows and data readiness, and update your internal calendar to avoid missed deadlines during the transition.

What Triggers A Scrutiny Notice In Maharashtra And How Should I Respond?

Common triggers include mismatches between GSTR-1 and GSTR-3B, ITC claimed beyond GSTR-2B, and e-way bill discrepancies. Respond within 30 days with a reconciliation statement, supporting documents, and, where applicable, a voluntary tax payment with interest to close the matter quickly.