GST Returns Due Dates: GSTR-1, GSTR-3B & GSTR-9 Complete Guide

GST Returns: What They Are and Why They Matter

A GST return is a document filed with the tax authorities that contains details of income, sales, purchases, and the tax collected and paid during a given period. Under India's Goods and Services Tax framework, registered taxpayers must file returns periodically so the government can verify that the right amount of tax has been declared and paid.

The three returns that affect the vast majority of regular taxpayers are GSTR-1 (statement of outward supplies), GSTR-3B (consolidated summary return with tax payment), and GSTR-9 (annual return). Filing all three accurately and on time is essential — not just to avoid penalties, but also to preserve your eligibility to claim Input Tax Credit (ITC), which directly affects your cash flow.

Missing a filing deadline can trigger late fees that compound daily, a block on your customers' ITC for the period, and — in repeated cases — best-judgment assessment and cancellation of your GSTIN by the department. Two recent changes raise the stakes further: from the July 2025 tax period the liability fields of GSTR-3B are hard-locked to your GSTR-1, and from August 2025 any return left unfiled for more than three years past its due date is permanently barred.

Who Must File GST Returns?

All taxpayers registered under GST must file returns. The specific forms and frequency vary based on registration type, turnover, and the scheme opted.

This guide focuses on GSTR-1, GSTR-3B, and GSTR-9, which apply to the majority of businesses — sole proprietors, partnerships, LLPs, private limited companies, and MSMEs registered under GST.

GSTR-1: Statement of Outward Supplies

GSTR-1 is a detailed statement of all sales and outward supplies made during the period. Every invoice, debit note, and credit note issued to your customers must be reported here. This data becomes the source from which your customers' auto-populated purchase register (GSTR-2B) is generated — making accuracy critical for the entire GST ecosystem. Since the July 2025 tax period it also auto-populates the liability fields of your own GSTR-3B, which are then locked.

What to report in GSTR-1

• B2B invoices (to registered businesses) — invoice-level detail
• B2C large invoices — interstate supplies to unregistered buyers above ₹1 lakh per invoice (threshold reduced from ₹2.5 lakh with effect from 1 August 2024)
• B2C small invoices — state-wise summary only
• Exports (with or without payment of IGST)
• Credit notes and debit notes issued
• HSN/SAC-wise summary of supplies (Table 12, now a mandatory drop-down)
• Advances received for future supply

Due dates

• Monthly filers (turnover > ₹5 crore): 11th of the following month (e.g., June supplies → 11th July).
• Quarterly filers (QRMP scheme, ≤ ₹5 crore): 13th of the month following quarter end (e.g., Apr–Jun quarter → 13th July).

IFF — Invoice Furnishing Facility (QRMP taxpayers)

Quarterly GSTR-1 filers can optionally use the Invoice Furnishing Facility (IFF) to upload B2B invoices for the first two months of each quarter. This lets your business customers see your invoices in their GSTR-2B without waiting until the quarter-end GSTR-1. IFF is due by the 13th of the following month for months 1 and 2 of the quarter. Month 3 invoices are reported in the regular quarterly GSTR-1. IFF is optional — if not used, all invoices are reported in the quarterly GSTR-1.

HSN reporting at a glance

Businesses with aggregate turnover above ₹5 crore must report a minimum 6-digit HSN code for both B2B and B2C supplies; those with turnover up to ₹5 crore report a minimum 4-digit code (mandatory for B2B, optional for B2C). From January 2025, HSN codes must be selected from the portal's drop-down list rather than typed manually, and Table 12 is split into separate B2B and B2C tabs.

GSTR-3B: Monthly/Quarterly Summary Return

GSTR-3B is a consolidated summary return in which you declare your total outward supplies, total ITC claimed, net tax liability, and make the actual tax payment. Unlike GSTR-1, it does not require invoice-level details — but it does require you to pay any outstanding tax liability before or at submission. A GSTR-3B filed without paying the tax due is treated as not filed.

An important change applies from the July 2025 tax period (filed in August 2025): the outward-liability fields in Tables 3.1 and 3.2, auto-populated from your GSTR-1/IFF, are now hard-locked and non-editable. If those figures are wrong, you must correct them at source through GSTR-1 or the amendment form GSTR-1A before filing GSTR-3B for the same period — you can no longer simply overtype the value in 3B. ITC fields (Table 4) remain editable for now, with hard-locking of ITC signalled for a later phase, so reconciling against GSTR-2B before you file remains essential.

Category X states (due 22nd) include Maharashtra, Gujarat, Karnataka, Tamil Nadu, Telangana, Andhra Pradesh, Kerala, Chhattisgarh, Madhya Pradesh, Goa and the southern/western UTs. Category Y states (due 24th) include Delhi, Uttar Pradesh, Rajasthan, Haryana, Punjab, West Bengal, Bihar, the north-eastern states and the northern UTs. Verify your state's category on the GST portal at the time of filing.

QRMP monthly tax payment

Even though QRMP taxpayers file GSTR-3B quarterly, they must still pay tax monthly for the first two months of each quarter via Form GST PMT-06 (due by the 25th of the following month). Two methods are available: (a) Fixed Sum Method — pay 35% of the net cash tax liability from the last quarterly GSTR-3B; (b) Self-Assessment Method — calculate and pay the actual liability for the month. Tax for the third month is paid along with the quarterly GSTR-3B.

GSTR-2B: Your Auto-Populated ITC Statement

While not a return you file, GSTR-2B is essential to the filing cycle. It is a static, auto-generated statement of available Input Tax Credit, generated by the GST portal on the 14th of each month (for monthly filers) based on GSTR-1/IFF filed by your suppliers up to the 13th. For QRMP quarterly filers, it is generated after the quarter-end filing deadline.

Under current GST rules, ITC is essentially restricted to invoices that appear in your GSTR-2B — the older provisional-ITC buffer has been withdrawn, so uncorroborated claims risk reversal with interest. Always reconcile your purchase register against GSTR-2B before filing GSTR-3B, and follow up with suppliers whose invoices are missing. The portal's Invoice Management System (IMS) lets you accept, reject, or keep invoices pending before they flow into GSTR-2B.

GSTR-9: Annual Return

GSTR-9 is the annual consolidation of all monthly/quarterly returns filed during a financial year. It reconciles the data declared across the year's GSTR-1s and GSTR-3Bs, flags any differences, and lets you account for omissions or mismatches. Think of it as the year-end summary of your GST compliance.

GSTR-9: key details

• Due date: 31st December of the year following the financial year (e.g., GSTR-9 for FY 2024-25 was due 31 December 2025; FY 2025-26 is due 31 December 2026).
• Who must file: All regular GST taxpayers, except Composition dealers (who file GSTR-4) and certain exempt categories.
• Turnover up to ₹2 crore: Filing is optional. This exemption is now a standing relief from FY 2024-25 onwards (Notification No. 15/2025–Central Tax), rather than a year-by-year waiver, though voluntary filing is permitted.
• Late fee: Slab-based by turnover (see below) — no longer a flat ₹200 per day.

GSTR-9 late fee — turnover slabs

GSTR-9C: reconciliation statement

Taxpayers with aggregate annual turnover exceeding ₹5 crore must also file GSTR-9C, a reconciliation statement between the audited financial statements and the GSTR-9. From FY 2020-21 onwards, GSTR-9C is self-certified by the taxpayer — the earlier requirement for a Chartered Accountant's certification was removed and has not been reinstated. Having a CA prepare it is still advisable for businesses without dedicated tax teams. GSTR-9C covers reconciliation of gross turnover (financial statements vs. GST returns), reconciliation of taxable turnover, ITC reconciliation, and details of tax paid.

What you can correct in GSTR-9

GSTR-9 lets you declare supplies and ITC that were omitted or incorrectly reported in the monthly/quarterly returns. Note, however, that the underlying ability to amend GSTR-1/GSTR-3B for a financial year ends at the earlier of 30 November of the following year or the date the annual return is filed, so GSTR-9 is largely a disclosure-and-reconciliation exercise rather than a fresh chance to claim credit. Annual return entries cannot reduce a liability already adjudicated or revive a refund already rejected.

QRMP Scheme: Simplified GST Compliance for Small Businesses

The Quarterly Return Monthly Payment (QRMP) scheme, introduced in January 2021, allows taxpayers with aggregate annual turnover up to ₹5 crore to file GSTR-1 and GSTR-3B quarterly while paying tax monthly. It cuts the number of these return filings from 24 a year (two monthly returns × 12) to 8 a year (two quarterly returns × 4 quarters).

Who can opt in

• Aggregate turnover ≤ ₹5 crore in the preceding financial year
• The taxpayer must have filed GSTR-3B for the previous month
• You can opt in or out at the start of each quarter (the opt-in window for a quarter runs from the 1st of the second month of the previous quarter to the last day of the first month of the quarter)
• New registrations can opt in immediately

Who cannot opt in

• Aggregate turnover > ₹5 crore in the preceding FY
• Persons required to deduct TDS (GSTR-7)
• E-commerce operators collecting TCS (GSTR-8)
• Non-resident taxable persons
• Persons filing GSTR-5/6

GST Return Due Dates — Consolidated Calendar

The table below shows the standard recurring due dates that apply from FY 2025-26 onwards. The government may extend deadlines for specific periods via notifications — always check the GST portal for the latest advisories.

Three-year filing bar: With effect from the August 2025 filing cycle, the GST portal will not accept any return (GSTR-1, GSTR-3B, GSTR-9, GSTR-9C and others) beyond three years from its original due date. The tax liability itself does not lapse — it can still be recovered with interest and penalty — but the window to file the return closes permanently, so clear any backlog well within the three-year limit.

Late Fees, Interest & Penalties

Late filing and late payment of GST attract separate charges. Late fees apply for delayed filing regardless of whether tax is due; interest applies on the unpaid tax amount. The maximum late fee for GSTR-1 and GSTR-3B is capped according to your turnover.

Interest on late payment

18% per annum is charged on the net tax liability (after eligible ITC) from the day after the due date until the date of actual payment. If you file GSTR-3B on time but pay only part of the tax, interest accrues on the unpaid portion.

24% per annum applies where excess ITC is claimed and utilised — this higher rate is a deterrent against wrongful ITC claims. Ensure your GSTR-2B reconciliation is complete before claiming credit.

5 Common GST Filing Mistakes to Avoid

1. Mismatches between GSTR-1 and GSTR-3B. With liability now hard-locked from GSTR-1, your 3B already mirrors your GSTR-1 — so errors must be fixed in GSTR-1/GSTR-1A first. Persistent mismatches still trigger scrutiny notices under Section 61 of the CGST Act.
2. Claiming ITC without verifying GSTR-2B. ITC claimed in GSTR-3B should not exceed what appears in your GSTR-2B. Claiming ineligible or unmatched ITC attracts reversal plus interest at 24% — far costlier than the original tax saved.
3. Incorrect HSN/SAC codes. Businesses with turnover above ₹5 crore must report 6-digit HSN codes; those up to ₹5 crore report 4-digit codes (mandatory for B2B). Manual entry is no longer allowed — pick from the drop-down. Wrong classification leads to incorrect tax rates and disputes.
4. Not filing a nil return. If you have no transactions, you must still file a nil GSTR-1 and nil GSTR-3B. Skipping zero-activity months is a common reason registrations get flagged or cancelled.
5. Letting old returns cross the three-year bar. Any return unfiled for over three years past its due date is permanently blocked from August 2025. Clear backlogs early — the tax still has to be paid even after the filing window shuts.

Filing GST Returns on the GST Portal

All GST returns are filed online at gst.gov.in using your GSTIN credentials. There is no government fee for filing returns — the portal is free to use. Professional fees apply only if you engage a CA, tax consultant, or a GST Suvidha Provider (GSP) to file on your behalf.

The portal has improved significantly in recent years, with auto-population, hard-locked liability fields, an integrated ledger showing your cash and credit balances, the Invoice Management System for ITC, and an advisory that flags potential mismatches before you submit. Businesses looking to verify the GSTIN details of their vendors — for invoice reconciliation or due diligence — can use the WeeDoo company search tool, which provides free access to GST registration data alongside MCA and director information.