GST Filing Services: Managed GSTR-1 & GSTR-3B Filing

GSTR-3B liability is locked to GSTR-1. From the July 2025 tax period, the tax liability in Table 3 of GSTR-3B is auto-populated from GSTR-1, GSTR-1A and IFF and cannot be edited, so corrections go through GSTR-1A before you file. ITC in Table 4 is auto-populated from GSTR-2B and stays editable, but credit is allowed only on invoices that appear in GSTR-2B (Section 16(2)(aa)), and a claim above GSTR-2B beyond the notified limit draws a DRC-01C intimation under Rule 88D. There is no notified "Zero Mismatch" rule that rejects the return, but 2B reconciliation still has to happen before the 20th. See our guide on [what can actually block GSTR-3B filing](/blog/gstr-3b-blocked-zero-mismatch-policy-2026).

IMS deemed acceptance is live. Every supplier invoice appears in the Invoice Management System for you to accept, reject, or keep pending before GSTR-2B is generated. Inaction counts as acceptance. Read [how IMS changes the GST workflow](/blog/ims-invoice-management-system-mandatory-gst-2026).

GST 2.0 rates apply. The four-tier structure (0%, 5%, 18%, 40%) has been in force since 22 September 2025; the 12% and 28% slabs were removed. If you billed any post-change supply at an old rate, issue a revised invoice or credit note to keep your buyer's GSTR-2B clean.

A GST return is the periodic statement every registered business files on the GST portal. For most regular taxpayers, two returns carry the monthly workload:

GSTR-1: Outward supplies (invoice-wise sales to registered buyers, summary of B2C sales)

GSTR-3B: Summary return with output tax, ITC claimed and net tax paid

GSTR-1 feeds your buyers' GSTR-2B, so a late or wrong GSTR-1 blocks their input tax credit too.

Law: CGST Act 2017 (Sections 37, 39, 44, 47, 50), CGST Rules 2017

Filing Deadlines (FY 2026-27):

• GSTR-1 (monthly): 11th of the following month
• GSTR-1 (QRMP): 13th of the month after the quarter, with optional IFF for B2B invoices
• GSTR-3B (monthly): 20th of the following month
• GSTR-3B (QRMP): 22nd or 24th of the month after the quarter, depending on your state
• GSTR-9: 31 December after the financial year

Late fee (Section 47): ₹50/day (₹20/day for nil returns), capped at ₹2,000 / ₹5,000 / ₹10,000 by turnover and ₹500 for nil returns

Interest (Section 50): 18% p.a. on tax paid late, on the net cash portion

Authority: GST Portal (https://www.gst.gov.in)

Mandatory if:

• You hold an active GSTIN, even with zero sales in the period (file a nil return)
• Registration is not cancelled or suspended

Frequency:

• Monthly GSTR-1 & GSTR-3B for regular taxpayers
• Quarterly GSTR-1 & GSTR-3B under QRMP (turnover up to ₹5 crore), with monthly tax payment via PMT-06
• Composition taxpayers file CMP-08 quarterly and GSTR-4 annually instead

Cost of Non-Filing:

• Late fee accrues daily until you file (capped by turnover)
• 18% interest on tax paid late
• GSTR-1 filing is blocked if GSTR-3B is pending, and e-way bill generation is blocked after two missed return periods
• Continuous non-filing (six months for regular taxpayers) can lead to cancellation of registration

1. Collect all sales invoices, credit notes and debit notes for the month

2. Collect purchase invoices and expense bills

3. Reconcile with bank statements

4. Identify taxable, exempt and nil-rated supplies

Your Action: Share invoice copies and bank statements

1. Upload invoice-wise B2B data and B2C summaries

2. Validate GSTINs, HSN summary and document series

3. File with EVC or DSC

4. Generate ARN (acknowledgment)

Our Action: We prepare, validate and file

1. Review supplier invoices in IMS (accept, reject or keep pending)

2. Match GSTR-2B against your purchase register

3. Flag missing or mismatched supplier invoices

4. Arrive at the eligible ITC figure

Our Action: Complete reconciliation before GSTR-3B

1. Compute net tax after eligible ITC

2. Generate challan (PMT-06) and pay cash liability

3. Offset liability in the electronic ledgers

4. File GSTR-3B and share the ARN with you

Our Action: Ensure on-time payment and filing

What goes wrong:

• Sales invoices left out of GSTR-1
• Your buyer cannot see the invoice in GSTR-2B and holds payment
• Mismatch between GSTR-1 and GSTR-3B triggers a DRC-01B intimation

How to avoid:

• Report every invoice, credit note and debit note
• Match GSTR-1 totals with GSTR-3B before filing
• Keep one invoice series per location

What goes wrong:

• Claiming credit from the purchase register instead of GSTR-2B
• Large gaps between ITC claimed and GSTR-2B trigger a DRC-01C intimation asking you to explain or pay
• Wrongly availed and utilised ITC attracts 18% p.a. interest under Section 50(3) on reversal

How to avoid:

• Claim only ITC reflected in GSTR-2B
• Act on IMS entries before 2B is generated
• Chase suppliers who have not filed GSTR-1

What goes wrong:

• GSTR-3B cannot be filed until cash liability is paid
• Each day of delay adds late fee and 18% p.a. interest
• Two missed periods block e-way bill generation

How to avoid:

• Pay GST before the 20th
• Keep enough cash ledger balance
• Use our monthly payment reminders

Self-serve GST software (ClearTax and similar):

• You or your accountant enter and upload data
• Good fit if you already have in-house accounting staff
• Reconciliation and portal errors stay your responsibility
• Pricing usually depends on GSTINs, invoices and modules chosen

Managed GST filing (Tax Garden):

• A named team prepares, reconciles and files GSTR-1 and GSTR-3B
• GSTR-2B and IMS reconciliation done before every GSTR-3B

• WhatsApp and email support from people who filed your return

For a detailed feature-by-feature view, read our [Tax Garden vs ClearTax comparison](/blog/taxgarden-vs-cleartax-sme-compliance-comparison-2026).

High Volume or Multi-GSTIN: Custom pricing after a volume review, with multi-GSTIN reconciliations.

Compare what filing actually costs in our [GST filing cost guide](/blog/gst-filing-cost-small-business-india-2026).