Most GST filing services are designed for a single registration in a single state. Mumbai is where that assumption breaks. This is India's head office city, and the typical file here is a company registered in Maharashtra with branches, warehouses or marketing offices in four other states, each with its own GSTIN, its own return calendar and its own scrutiny officer.
| Question | Short answer for Mumbai |
|---|---|
| Monthly filing | GSTR-1 by the 11th, GSTR-3B by the 20th of the following month. |
| Quarterly filing under QRMP | Maharashtra is a Category X state, so quarterly GSTR-3B is due on the 22nd, not the 24th. GSTR-1 quarterly by the 13th. |
| The head office return most Mumbai groups have missed | GSTR-6. Input Service Distributor registration became mandatory on 1 April 2025 and the return is due by the 13th. |
| Cross-charge for third party common services | No longer available. From 1 April 2025 that credit has to move through the ISD route or the branch may lose it. |
| E-invoicing | If aggregate annual turnover is INR 10 crore or more, an invoice older than 30 days is rejected by the IRP. Live since 1 April 2025. |
| Can you still fix GSTR-3B | No. Auto-populated liability has been hard-locked since the July 2025 tax period. Corrections run through GSTR-1A. |
| Where a notice comes from | State side, GST Bhavan Mazgaon. Central side, the Mumbai Zone at Churchgate, unless you are in Thane, Navi Mumbai, Bhiwandi, Palghar or Raigad, in which case it is a different commissionerate entirely. |
| Hard stop | Three years from the due date. After that the portal bars the return and you need the unbarring application. |
Most GST filing services are designed for a single registration in a single state. Mumbai is where that assumption breaks. This is India's head office city, and the typical file here is a company registered in Maharashtra with branches, warehouses or marketing offices in four other states, each with its own GSTIN, its own return calendar and its own scrutiny officer.
That shape creates a problem that only became compulsory last year. If your Mumbai head office receives invoices for services used by all of those branches, the software subscription, the retainer, the audit fee, the advertising spend, you can no longer cross-charge that credit out. Input Service Distributor registration became mandatory on 1 April 2025 and the credit has to travel through GSTR-6.
We file GSTR-1, GSTR-3B, GSTR-6, GSTR-9 and GSTR-9C, reconcile input tax credit against GSTR-2B through the Invoice Management System before the liability locks, and run one calendar per registration rather than pretending they are all the same.
| Return or payment | Who files it | Due date |
|---|---|---|
| GSTR-1 | Monthly filers, turnover above INR 5 crore or opted out of QRMP | 11th of the following month |
| GSTR-1 quarterly | QRMP filers, turnover up to INR 5 crore | 13th of the month following the quarter |
| IFF, optional | QRMP filers wanting buyers to get credit sooner | 13th of the following month, months 1 and 2 of the quarter |
| GSTR-6 | Input Service Distributors | 13th of the following month, including nil |
| GSTR-3B monthly | Monthly filers | 20th of the following month |
| GSTR-3B quarterly | QRMP filers registered in Maharashtra, Category X | 22nd of the month following the quarter |
| PMT-06 challan | QRMP filers, monthly tax deposit | 25th of the following month, months 1 and 2 of the quarter |
| GSTR-7 and GSTR-8 | TDS deductors and e-commerce operators collecting TCS | 10th of the following month |
| GSTR-9 | Aggregate turnover above INR 2 crore | 31 December following the financial year |
| GSTR-9C | Aggregate turnover above INR 5 crore | 31 December, filed with GSTR-9 |
| PTRC return | Maharashtra employers deducting professional tax | Monthly or annual by prior year liability, on mahagst.gov.in |
Note the 13th. If you are an ISD, GSTR-6 falls one clear day after GSTR-1. There is very little room, because the credit shown in GSTR-6A only populates once your suppliers have filed their GSTR-1. A group that starts its ISD workings on the 12th will miss.
If your group holds GSTINs outside Maharashtra, the quarterly GSTR-3B date changes with the state. A Mumbai head office with a Kolkata or Delhi branch is filing on the 22nd for one and the 24th for the other, in the same quarter, for the same company.
Section 2(61) and Section 20 of the CGST Act were amended by the Finance Act, 2024 with effect from 1 April 2025. What was permissive language became mandatory. If an office receives tax invoices for input services used by more than one distinct person under the same PAN, that office must hold an ISD registration and distribute the credit through it.
This is the distinction that matters, and it is the one most often got wrong. ISD applies where a third party bills one office for services consumed across several branches: the enterprise software licence, the group audit fee, the national advertising contract, the legal retainer, the insurance premium. Cross-charge still exists, but only for services one branch actually renders to another internally. It is no longer a substitute for ISD on externally procured common services.
The consequence of ignoring it is not procedural. If you cross-charged third party common services after 31 March 2025 instead of distributing them, the receiving branch may not be entitled to the credit at all, because the statutory route was not followed. That is a reversal at the branch, with interest, plus penalty exposure under Section 122, sitting on top of a credit you thought you had banked.
The mechanics are unforgiving on timing. Credit available with the ISD in a month has to be distributed in that same month. It cannot be parked. Distribution follows the Rule 39 formula, in proportion to each recipient's turnover, except where a credit belongs to one branch exclusively, in which case it goes there in full. Eligible and ineligible credit are distributed separately, and reverse charge credit is dealt with separately again.
There is a practical step that has nothing to do with the return and everything to do with whether it works. Your vendors have to raise their invoices on the ISD registration number, not on the regular Maharashtra GSTIN. If nobody tells them, the credit lands in the wrong registration and the ISD has nothing to distribute.
GSTN lowered the reporting threshold from INR 100 crore to INR 10 crore of aggregate annual turnover with effect from 1 April 2025. If you are above that line, an invoice, credit note or debit note cannot be reported on the Invoice Registration Portal more than 30 days after its date. An invoice dated 1 April cannot be reported after 30 April. The validation sits inside the portal and there is no override.
An invoice that misses the window gets no IRN, which means it is not a valid tax invoice, which means your customer gets no credit. Fixing it involves cancelling and re-issuing with a fresh date and number, which creates its own reconciliation mess and, if it crosses a month end, a conversation about which period the revenue belongs in.
This bites hardest in the sectors Mumbai runs on. Agencies and consultancies that raise invoices only on client sign-off, media businesses working to campaign completion, and anyone whose billing waits on a certification cycle. If your commercial process routinely puts three or four weeks between service delivery and invoice issue, the 30 day window is now the binding constraint on it, not your client's approval calendar.
GSTN Advisory No. 606 dated 7 June 2025 made the auto-populated outward liability in GSTR-3B non-editable from the July 2025 tax period. Tables 3.1 and 3.2 are read only. There is no manual entry and no override.
GSTR-1 and GSTR-1A are now the single source of truth for liability, and GSTR-3B is only the mechanism for discharging it. A wrong GSTIN, a wrong place of supply or a wrong rate in GSTR-1 is locked into what you pay. GSTR-1A is the only correction route and it can be filed once for a period, before GSTR-3B for that same period.
For a Mumbai group this reshapes the month. The deadline that governs your accuracy is the 11th, not the 20th. Inward invoices and credit notes have to be actioned in the Invoice Management System while the period is still open, because a credit note rejected and left unattended raises your supplier's liability and cuts your credit. Multiply that across five registrations and it stops being something one person does on the 19th.
| Package | Fee | What it covers |
|---|---|---|
| Quarterly, QRMP filers | From INR 999 per quarter | GSTR-1, GSTR-3B, PMT-06 challans, IMS actions, credit reconciliation |
| Monthly, single registration | On quote, based on invoice volume | GSTR-1, GSTR-3B, IMS, GSTR-2B reconciliation, monthly position report |
| Multi-state, multiple GSTINs | On quote, per registration with a group rate | All of the above across each registration, with a consolidated position |
| ISD registration and GSTR-6 | On quote | ISD set-up, vendor invoicing instructions, Rule 39 allocation, monthly GSTR-6 |
| Annual return, GSTR-9 and GSTR-9C | On quote | Annual return and reconciliation statement where the turnover thresholds are crossed |
| Backlog and pending returns | On quote | Triage by due date, late fee computation, filing before the three year bar |
Every fee above is a professional fee and excludes GST. Late fees, interest and any government charges are paid by you at actuals and none of it sits inside our fee.
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.
| Trigger | Charge |
|---|---|
| Late GSTR-1 or GSTR-3B with liability | INR 50 per day, being INR 25 CGST and INR 25 SGST |
| Late nil GSTR-1 or GSTR-3B | INR 20 per day, being INR 10 CGST and INR 10 SGST |
| Late fee cap, per return | INR 2,000 up to INR 1.5 crore turnover, INR 5,000 from INR 1.5 crore to INR 5 crore, INR 10,000 above INR 5 crore |
| Late GSTR-6 | INR 100 per day, being INR 50 CGST and INR 50 SGST |
| Interest on unpaid tax | 18 per cent a year from the day after the due date |
| Interest on excess credit claimed and utilised | 24 per cent a year |
| Late GSTR-9 | INR 200 per day, capped at 0.5 per cent of turnover in the state |
The fee is rarely what hurts. A missed return blocks the next period, so one skipped month becomes a chain across a registration. Your buyers stop seeing your invoices in their GSTR-2B, and in Mumbai's vendor ecosystem a supplier whose credit does not flow gets replaced before anyone tells him why.
The Finance Act, 2023 inserted time limits into Sections 37, 39, 44 and 52 of the CGST Act, notified by Notification No. 28/2023 - Central Tax dated 31 July 2023 with effect from 1 October 2023. A return cannot be furnished after three years from its due date. GSTN brought the validation live on the portal from the July 2025 tax period and issued a further advisory on 29 October 2025.
It covers GSTR-1, GSTR-1A, GSTR-3B, GSTR-4, GSTR-5, GSTR-6, GSTR-7, GSTR-8, GSTR-9 and GSTR-9C. GSTR-6 sitting on that list matters for groups that took ISD registration, filed for a few months and then stopped.
Once a period is barred the liability survives. Tax, interest and penalty remain recoverable and you lose the ability to self-assess. GSTN has since launched an Application for Unbarring Returns module on the portal under Services, Returns, which is an administrative route rather than an entitlement. If your group carries dormant registrations in states you no longer operate in, that backlog has a clock on it and should be triaged oldest first.
| Reference | Relevance |
|---|---|
| Sections 2(61) and 20, CGST Act, 2017, as amended by the Finance Act, 2024 | Input Service Distributor registration and distribution made mandatory, commenced 1 April 2025 by Notification No. 16/2024 - Central Tax |
| Rule 39, CGST Rules, 2017 | Manner of distribution of credit by an Input Service Distributor, as amended by Notification No. 12/2024 - Central Tax dated 10 July 2024 |
| GSTN Advisory No. 606 dated 7 June 2025 | Auto-populated outward liability in GSTR-3B Tables 3.1 and 3.2 non-editable from the July 2025 tax period. Corrections through GSTR-1A. |
| Notification No. 28/2023 - Central Tax dated 31 July 2023 | Three year bar on furnishing returns under Sections 37, 39, 44 and 52, effective 1 October 2023 and enforced on the portal from the July 2025 tax period |
| QRMP staggering, effective from the January 2021 tax period | Maharashtra is a Category X state, so quarterly GSTR-3B falls due on the 22nd |
| Notification No. 15E/2018 - State Tax dated 29 June 2018 | Maharashtra intra-state e-way bill threshold of INR 1 lakh consignment value |
| E-invoice reporting threshold, effective 1 April 2025 | 30 day reporting window on the IRP for taxpayers with aggregate annual turnover of INR 10 crore or more |
Authority sources: the GST common portal at gst.gov.in, the e-invoice portal at einvoice.gst.gov.in and the Maharashtra GST Department at mahagst.gov.in. Verified 04 August 2026.
On the state side, the Maharashtra GST Department divides Mumbai into zones and nodal divisions named after suburbs, and almost all of them are physically housed at GST Bhavan, Mazgaon, Mumbai 400010. Andheri, Goregaon, Kandivali, Borivali, Ghatkopar, Mulund and Chembur are nodal division names, not separate buildings. If you are called in, you are going to Mazgaon.
On the central side, the Mumbai Zone is headed by a Principal Chief Commissioner at GST Bhavan, 115 Maharishi Karve Marg, Churchgate, Mumbai 400020, with executive commissionerates for Mumbai Central, Mumbai East, Mumbai South, Mumbai West, Thane, Thane Rural, Palghar, Bhiwandi, Belapur, Navi Mumbai and Raigad.
That last list is the part worth reading twice. A business that describes itself as a Mumbai business but operates from Vashi, Belapur, Thane, Bhiwandi or Panvel is not under a Mumbai commissionerate. It is under Navi Mumbai, Belapur, Thane, Bhiwandi or Raigad, with a different audit commissionerate and a different appellate forum. When an ASMT-10 lands, the reply window runs from the date on the notice, and time spent working out which office holds the file is time taken out of that window.
Same city: GST Registration in Mumbai. Sibling city page: GST Return Filing in Pune. If common input service invoices land at your Mumbai head office and the services are used by more than one GSTIN, start with ISD registration, because the GSTR-6 obligation follows from it.
The 22nd of the month following the quarter. Maharashtra is a Category X state under the QRMP staggering, alongside Gujarat, Karnataka, Goa, Madhya Pradesh, Chhattisgarh, Kerala, Tamil Nadu, Telangana and Andhra Pradesh. The 24th applies to Category Y states such as West Bengal, Delhi and Uttar Pradesh. If your group holds registrations in both groups, you are filing on two dates in the same quarter.
If any office of yours receives tax invoices from a third party for services used by more than one GSTIN under the same PAN, then yes, and it has been mandatory since 1 April 2025. The common examples are enterprise software, group audit and legal fees, national advertising, and insurance. If in doubt, look at where the vendor invoices physically arrive rather than at where the service is consumed.
Not for third party common services. Cross-charge survives only for services one branch genuinely renders to another internally. Using it for externally procured common services after 31 March 2025 risks the receiving branch losing the credit outright, because the statutory route was not followed, with interest and penalty exposure on top.
The 13th of the following month, and yes, a nil return is still filed while the registration is active. The timing is tight because GSTR-6A only populates once your suppliers have filed their GSTR-1. Credit available in a month must also be distributed within that same month, so it cannot be carried forward inside the ISD.
If your aggregate annual turnover is INR 10 crore or more, you cannot report an invoice, credit note or debit note on the Invoice Registration Portal more than 30 days after its date. The threshold dropped from INR 100 crore to INR 10 crore with effect from 1 April 2025. A document that misses the window gets no IRN, so it is not a valid tax invoice and your customer gets no credit. The only fix is to cancel and re-issue with a fresh date.
No. Since the July 2025 tax period, the auto-populated outward liability in Tables 3.1 and 3.2 is non-editable, under GSTN Advisory No. 606 dated 7 June 2025. Corrections go through GSTR-1A for the same tax period, before GSTR-3B is filed, and GSTR-1A can be filed once per period.
It is a Maharashtra registration, so the GSTIN still begins with 27 and the return calendar is the same. But the administering central office is not a Mumbai commissionerate. Thane, Thane Rural, Bhiwandi, Palghar, Belapur, Navi Mumbai and Raigad are separate commissionerates within the Mumbai Zone, each with its own audit and appellate machinery. It matters when a notice arrives, not when you file.
It will not appear in your GSTR-2B, and with GSTR-3B hard-locked you cannot simply take it anyway. This is why we reconcile against GSTR-2B rather than the purchase register and name the defaulters each month, so you can chase them while the period is still open rather than at annual return time.
The portal bars them. Under the Finance Act, 2023 and Notification No. 28/2023 - Central Tax, returns under Sections 37, 39, 44 and 52 cannot be furnished after three years from the due date, enforced on the portal from the July 2025 tax period. GSTR-6 is on that list. The liability does not lapse, and GSTN's Application for Unbarring Returns module is an application to be justified rather than an automatic right.
Yes. We start by reconciling what has been filed against your books across every registration, quantify late fee and interest exposure, check whether any period is near the three year bar, and review whether an ISD registration should already have been in place. You get that position before you commit to a retainer.
Tell us what you need and a real CA calls you back, with no scripts and no transfers. Call 72783 76654. Mon - Sat, 10:00 AM - 7:00 PM IST.
Reviewed by CA & CS Team - CorporateWalla · Last Updated 04 August 2026 · · Sources: GST common portal, Maharashtra GST Department, E-invoice portal
Canonical: https://corporatewalla.com/mumbai/gst-return-filing
