GST filing can feel very confusing and hectic GSTR-1, 3B, 9C… what do all these even mean? Whether you’re just starting your business or already knee-deep in returns, understanding which GSTR form applies to you (and when!) is the first step to staying compliant and stress-free.

As a GST consultant in Chennai, I’ve seen even the most seasoned entrepreneurs get tripped up by missed deadlines or choosing the wrong form. So, I’ve put together a clear, easy-to-follow breakdown of all the GSTR forms, requirements for error-free filing, and mistakes to avoid.

Let’s decode the chaos together.

Why GST Filing Matters?

Every business registered under GST has a legal responsibility to file returns. These forms help:

  • Report sales and purchases
  • Pay taxes
  • Claim Input Tax Credit (ITC)
  • Maintain compliance with the GST Act

Missing deadlines, wrong inputs, or even skipping a “NIL return” can lead to heavy fines, blocked credits, or even cancellation of your GSTIN.

But don’t worry—we’ve got this. Whether you’re managing your own GSTR filing in Chennai or planning to outsource, this guide has your back.

GSTR-1: Report Your Sales (Outward Supplies)

Purpose: To report all your outward supplies—basically, your sales and invoices issued.

Who Should File:
All regular registered taxpayers (excluding composition taxpayers, non-residents, ISDs, etc.)

Filing Frequency:

  • Monthly – If your annual turnover exceeds ₹5 crore
  • Quarterly (QRMP) – If turnover is below ₹5 crore

Due Date:

  • Monthly: 11th of the following month
  • Quarterly: 13th of the month following the quarter

Details to Report:

  • Invoice-wise details of B2B sales
  • Consolidated B2C sales
  • Exports
  • Credit/debit notes
  • Amendments, if any

Mistakes to Avoid:

  • Mismatched invoice numbers
  • Missing invoices
  • Not reporting exports
  • Delaying GSTR-1 while GSTR-3B is already filed

Pro Tip: Buyers rely on your GSTR-1 to claim their Input Tax Credit (ITC). Any mismatch can hurt your business relationships.

GSTR-3B: Summary Return & Tax Payment

Purpose: A monthly summary of all sales, purchases, input tax credits, and tax liability. You pay tax via this form.

Who Should File:
All regular taxpayers under GST

Filing Frequency:

  • Monthly – For most businesses
  • Quarterly – If under QRMP scheme

Due Date:

  • Monthly: 20th of the next month
  • Quarterly: 22nd or 24th, based on state group

Details to Report:

  • Outward taxable supplies
  • Inward supplies (with/without reverse charge)
  • ITC claimed
  • Tax payable and paid

IMPORTANT:
From July 2025, once you file GSTR-3B, you can’t edit it. Triple-check before submission.

Mistakes to Avoid:

  • Reporting tax values without proper ITC reconciliation
  • Not paying the correct amount
  • Forgetting reverse charge entries

GSTR 3B filing

GSTR-4: Composition Scheme Annual Return

Purpose: Annual summary return for taxpayers under the composition scheme who pay GST at a fixed rate.

Who Should File:
All registered composition taxpayers

Filing Frequency:
Annually

Due Date:
30th April of the following financial year

Details to Report:

  • Summary of outward supplies
  • Tax liability
  • Late fee or interest (if any)

Mistakes to Avoid:

  • Filing quarterly returns (composition taxpayers shouldn’t)
  • Overstating turnover
  • Skipping NIL returns

GSTR-5: For Non-Resident Taxpayers

Purpose: Monthly return for non-resident taxable persons (NRTPs) who have temporary GST registration in India.

Who Should File:
NRTPs supplying goods/services in India

Filing Frequency:
Monthly

Due Date:
20th of the following month

Details to Report:

  • All taxable outward/inward supplies
  • Tax payable and paid
  • Credit/debit notes

Mistakes to Avoid:

  • Missing due date (as NRTPs operate under strict timelines)
  • Incorrectly claiming ITC (NRTPs are not eligible)

To know More

GSTR-5A: For OIDAR Service Providers

Purpose: For foreign companies providing Online Information and Database Access or Retrieval (OIDAR) services to non-taxable Indian customers.

Who Should File:
Foreign service providers like Netflix, Adobe, etc.

Due Date:
20th of the following month

Mistakes to Avoid:

  • Confusing with GSTR-5
  • Skipping filing assuming no tax in India

GSTR-6: Input Service Distributors (ISD)

Purpose: For businesses that distribute ITC from a head office to branches (as ISD).

Who Should File:
Registered ISDs only

Due Date:
13th of the following month

Details to Report:

  • Total ITC received
  • ITC distributed
  • Distribution summary (GSTIN-wise)

Mistakes to Avoid:

  • Distributing ITC to wrong branches
  • Missing supplier GSTINs

GSTR-7: TDS Return under GST

Purpose: For businesses required to deduct TDS under GST

Who Should File:
Government departments, agencies, and notified taxpayers

Due Date:
10th of the following month

Details to Report:

  • GSTINs of deductees
  • Invoice value and tax deducted

Mistakes to Avoid:

  • Delays in payment
  • Missing deductee details
  • Wrong GSTIN of vendors

GSTR-8: For E-Commerce Operators (TCS)

Purpose: To report Tax Collected at Source (TCS) on supplies made through the e-commerce platform

Who Should File:
Operators like Amazon, Flipkart, or private portals

Due Date:
10th of the following month

Details to Report:

  • GSTIN-wise TCS collected
  • Supplies made through the portal
  • Adjustments, if any

Mistakes to Avoid:

  • Delayed TCS deposits
  • Skipping credit note adjustments

GSTR-9: Annual Return

Purpose: Consolidated summary of all returns filed in a year

Who Should File:
All regular taxpayers (Turnover < ₹2 crore = optional)

Due Date:
31st December of the next financial year

Details to Report:

  • Total sales, purchases
  • ITC claimed
  • Tax paid
  • Adjustments

Mistakes to Avoid:

  • Mismatched values with GSTR-1 and 3B
  • Skipping reconciliation

GSTR 9 filing

GSTR-9C: GST Audit & Reconciliation Statement

Purpose: Reconciliation between GST returns and audited financials

Who Should File:
Businesses with annual turnover above ₹5 crore

Due Date:
Along with GSTR-9

Requirements:

  • Audit by CA/CMA
  • Reconciliation report
  • Certification

Mistakes to Avoid:

  • Not hiring a qualified auditor
  • Incomplete disclosures

GSTR-10: Final Return on Cancellation

Purpose: Filed when your GST registration is cancelled or surrendered

Due Date:
Within 3 months of cancellation date

Details to Report:

  • Closing stock with tax liabilities
  • Final liabilities

Mistakes to Avoid:

  • Delays leading to penalties
  • Not reconciling stock properly

GSTR-11: For UIN Holders (Embassies, UN Bodies)

Purpose: To claim a refund of taxes paid on inward supplies

Who Should File:
UIN holders only

Due Date:
Depends on inward supplies made

Filing GST Returns Error-Free: What You Need

Whether you’re doing GSTR filing in Chennai yourself or through an accountant, here’s a checklist for error-free compliance:

✅ What You Need:

  • Valid GSTIN
  • Invoices (with GST breakup)
  • Purchase and sales register
  • Debit/credit notes
  • HSN/SAC codes
  • Payment challans
  • Bank statements (if applicable)

Good Practices:

  • Reconcile books with GST returns
  • File NIL returns even when inactive
  • Stay updated with filing due dates
  • Use accounting software or GST return filing portals
  • Maintain digital backup of all GST records

Mistakes to Avoid When Filing GSTR

Here’s a list of common errors you can (and should) avoid:

❌ Filing GSTR-3B before GSTR-1 (can cause ITC mismatch)
❌ Missing out on B2B invoices
❌ Claiming ineligible ITC
❌ Using wrong GSTINs or invoice numbers
❌ Skipping quarterly filing under QRMP
❌ Not paying late fees or interest
❌ Forgetting NIL returns

Why Hire a GST Consultant in Chennai?

Let’s face it—GST filing isn’t just “filling a form”. It involves regular updates, reconciliations, and a strong understanding of compliance rules.

Here’s why many businesses prefer hiring a GST consultant:

  • Personalized advisory for your business model
  • Local understanding of state-wise variations
  • Timely alerts for due dates
  • Prevention of errors and notices
  • Seamless handling of audits and reconciliations

If you’ve been spending hours trying to fix return errors or responding to GST notices, now is the time to let a professional handle it.

GST filing doesn’t have to feel like a burden. With the right knowledge and a bit of planning, you can handle it confidently or better yet, partner with an expert.

Whether you’re a freelancer in Kodambakkam, a boutique owner in Mylapore, or a startup in Tidel Park, the rules are the same but the guidance you get can make all the difference. Need help with GSTR filing in Chennai? Let’s take the stress out of tax season. Contact a trusted GST consultant in Chennai today and get your returns sorted—accurately, on time, and hassle-free.