GST Compliance Calendar 2026: GSTR-1, GSTR-3B, GSTR-9/9C, CMP-08 Due Dates and QRMP Explained

GST Compliance Calendar 2026: GSTR-1, GSTR-3B, GSTR-9/9C, CMP-08 Due Dates and QRMP Explained

Missing a GST return deadline in India isn't just an administrative slip — it triggers late fees, interest on tax dues, and in repeated cases can even block your ability to generate e-way bills or claim input tax credit smoothly. For founders running lean teams, keeping track of which return is due when, and under which scheme, quickly becomes one of the most nagging parts of running a compliant business.

This guide lays out the GST compliance calendar for 2026 in a practical, sequential way — starting with the returns every regular taxpayer must know, moving into the QRMP scheme for smaller businesses, the annual return and reconciliation statement, the composition scheme return, and finally the late fee and interest exposure if you slip. Because GST due dates and late fee structures are amended periodically by the GST Council and CBIC through notifications, always confirm the exact current date for your filing period on the GST portal or with your CA before relying on any specific date below.

What the GST Compliance Calendar Covers

The GST compliance calendar is the recurring cycle of returns and statements every GST-registered business must file, based on its registration type (regular or composition), turnover, and chosen filing frequency. Broadly, it includes:

• GSTR-1 — the outward supply (sales) statement
• GSTR-3B — the summary return used to pay tax and claim input tax credit
• GSTR-9 and GSTR-9C — the annual return and reconciliation/audit statement
• CMP-08 — the quarterly statement for taxpayers under the composition scheme
• Invoice Furnishing Facility (IFF) — an optional monthly upload for QRMP taxpayers in the first two months of a quarter
• Other periodic returns such as GSTR-4 (annual return for composition dealers), GSTR-5/5A for non-resident and OIDAR suppliers, and GSTR-6 for input service distributors, which apply to specific categories of taxpayers

Each of these has a different periodicity and due date, and the correct due date can also shift depending on turnover slabs, the state in which the business is registered, and any extensions notified by the government during the year — extensions have become fairly common around festive periods and portal glitches, so it's worth treating published due dates as the default rather than an absolute guarantee.

Who Needs to Follow This Calendar

• Every regular GST-registered business — proprietorships, partnerships, LLPs, and companies — must file GSTR-1 and GSTR-3B on a monthly or quarterly basis depending on turnover and the scheme chosen
• Composition scheme taxpayers (small businesses with turnover below the composition threshold who have opted for the scheme) must file CMP-08 quarterly and GSTR-4 annually
• Businesses with aggregate turnover above the prescribed threshold (commonly cited around Rs 5 crore, though this should be verified for the relevant year) are generally required to file GSTR-9C along with the annual return, in addition to GSTR-9
• E-commerce operators, input service distributors, and non-resident taxable persons follow separate return schedules specific to their category
• Every taxpayer who has obtained GST registration, even if there is no business activity in a given period, since NIL returns still need to be filed to avoid late fees and potential registration cancellation for continued non-filing

Step-by-Step: Setting Up Your GST Filing Calendar

1. Identify your filing frequency. Determine whether you fall under monthly GSTR-1/GSTR-3B filing or have opted for the QRMP (Quarterly Return Monthly Payment) scheme based on turnover in the preceding financial year.
2. Confirm your GSTR-1 due date. Monthly filers typically file GSTR-1 by a fixed date early in the following month; QRMP filers file GSTR-1 quarterly, with an optional IFF upload for the first two months of each quarter.
3. Confirm your GSTR-3B due date. This can vary by state group under the QRMP scheme, so check whether your state falls in the category with an earlier or later cut-off date.
4. Set up monthly tax payment via PMT-06 if you are on QRMP, since even though the return is quarterly, tax must generally be deposited monthly using a fixed sum or self-assessment method.
5. Reconcile GSTR-2B with purchase records before finalising GSTR-3B each period, to ensure input tax credit claimed matches what suppliers have reported.
6. File CMP-08 quarterly if registered under composition, along with the tax payment for that quarter.
7. Prepare for annual filing — reconcile books of account, e-way bill data, and monthly/quarterly returns before filing GSTR-9, and arrange GSTR-9C reconciliation if your turnover crosses the applicable threshold.
8. Build a buffer period into your internal calendar — aim to have data ready at least 4-5 days before the statutory due date to accommodate portal load issues, common near deadline dates.
9. Track amendments and extensions — subscribe to GST portal notifications or rely on your CA to flag any date extensions or scheme changes during the year.

Documents and Data Needed for Each Filing

• Sales invoices and credit/debit notes for GSTR-1, ideally exported directly from your accounting or billing software
• Purchase invoices and GSTR-2B auto-drafted statement for input tax credit reconciliation before GSTR-3B
• E-way bills generated during the period, to cross-check with reported outward supplies
• Bank statements, to verify that tax payments match books of account
• HSN/SAC-wise summary of supplies, since GSTR-1 requires HSN-level reporting beyond a certain turnover
• Reverse charge mechanism (RCM) records, for any tax payable under reverse charge
• Audited financial statements, for GSTR-9C reconciliation where applicable
• Composition scheme turnover records, for CMP-08 and GSTR-4 filers
• Details of ineligible input tax credit and blocked credits, to ensure they are correctly excluded

Indicative Due Dates for 2026 (Verify Before Filing)

While exact dates should always be confirmed on the GST portal, the broad pattern that has generally applied is as follows:

• GSTR-1 (monthly filers): typically due within the first two weeks of the following month
• GSTR-1 (QRMP/quarterly filers): typically due within about three to four weeks after the end of the quarter, with optional IFF uploads for month 1 and month 2 of the quarter
• GSTR-3B (monthly filers): typically due around the 20th of the following month
• GSTR-3B (QRMP filers): typically due around the 22nd or 24th of the month following the quarter, depending on the state group the business belongs to
• CMP-08 (composition scheme): typically due within about 18 days after the end of the quarter
• GSTR-4 (composition annual return): typically due by around the end of June following the financial year
• GSTR-9 (annual return): typically due by around 31 December following the end of the financial year, though this has seen extensions in several years
• GSTR-9C (reconciliation statement): generally due alongside GSTR-9 for taxpayers above the applicable turnover threshold

Because these dates are subject to notification-based changes and extensions almost every year, treat the above as a starting reference and always cross-check against the current GST Council notifications before the filing month arrives.

Fees and Costs Involved

There is no government fee to file GST returns themselves — filing is free on the GST portal. The cost most businesses incur relates to:

• Professional/accounting fees for return preparation, reconciliation, and filing, which vary based on transaction volume and complexity and are usually charged monthly, quarterly, or as an annual retainer
• Late fees, which apply per return per day of delay beyond the due date, generally split between CGST and SGST components; late fee rates and any capping (including reduced caps for NIL returns) have been revised by the government from time to time, so always check the current rate applicable to your filing period rather than assuming a fixed figure
• Interest on delayed tax payment, generally computed on the net tax liability from the day after the due date until the date of actual payment, at a rate specified under the GST law — this rate should also be verified for the relevant period since it can differ between voluntary and delayed compliance scenarios
• GSTR-9C certification/reconciliation cost, where a chartered accountant's involvement is typically needed to prepare and certify the reconciliation between audited financials and GST returns

Consequences of Missing Deadlines and Common Pitfalls

• Late fee accumulation — even a short delay attracts late fees for every day of default, which can add up quickly across multiple return types
• Interest on unpaid tax — interest continues to accrue on outstanding tax until actual payment, regardless of whether the return itself is later filed
• Blocking of e-way bill generation — continued non-filing of GSTR-3B or CMP-08 beyond a certain number of periods can restrict the ability to generate e-way bills, disrupting supply chains
• Input tax credit mismatches — delayed filing by a supplier can affect the recipient's ability to claim input tax credit smoothly, since credit availability is closely tied to counter-party compliance under the current return framework
• Show cause notices and cancellation risk — sustained non-filing over consecutive periods can lead to notices and, eventually, cancellation of GST registration
• Rushed, error-prone annual filings — treating GSTR-9/9C as an afterthought instead of reconciling monthly leads to last-minute discrepancies that are harder to explain and correct
• QRMP payment miscalculation — businesses on QRMP sometimes forget that monthly tax payment via PMT-06 is still required even though the return itself is quarterly, leading to interest exposure despite timely quarterly filing
• Ignoring GSTR-2B reconciliation — skipping regular reconciliation between books and the auto-drafted GSTR-2B often surfaces as a large, hard-to-trace mismatch at year-end

FAQs

What is the difference between GSTR-1 and GSTR-3B?

GSTR-1 is a detailed statement of outward supplies (sales) reported invoice-wise or summary-wise, while GSTR-3B is a summary return used to declare total tax liability, claim input tax credit, and make the actual tax payment for the period.

Who is eligible for the QRMP scheme?

Registered taxpayers whose aggregate turnover in the preceding financial year is below the prescribed threshold (commonly around Rs 5 crore, though this should be verified) can opt for QRMP, allowing them to file GSTR-1 and GSTR-3B quarterly while still paying tax monthly.

Is GSTR-9 mandatory for every GST-registered business?

Filing requirements and thresholds for GSTR-9 have changed over the years, including relaxations for smaller taxpayers in certain years, so it's important to check the current threshold and any exemption notified for the relevant financial year rather than assuming it always applies uniformly.

What happens if I file a NIL return late?

Even NIL returns attract late fees for delayed filing, though the fee is often capped at a lower amount compared to returns with actual tax liability — the exact current cap should be verified since it has been revised previously.

Can I revise a GST return after filing?

GST returns generally cannot be revised once filed; corrections for errors or omissions are typically made through amendments in a subsequent period's return rather than by revising the original filing.

Do composition scheme taxpayers need to file GSTR-1 and GSTR-3B?

No, composition scheme taxpayers file CMP-08 quarterly for tax payment and GSTR-4 annually instead of the regular GSTR-1/GSTR-3B cycle applicable to normal taxpayers.

What is GSTR-9C and who needs to file it?

GSTR-9C is a reconciliation statement between the audited financial statements and the annual return, generally required for taxpayers whose turnover exceeds a specified threshold in a financial year, and it typically needs to be certified in the prescribed manner before filing.

How is interest calculated on delayed GST payment?

Interest is generally computed on the net tax liability outstanding, calculated from the day following the due date until the date the tax is actually paid, at the rate prescribed under the GST law for the relevant period — always confirm the current applicable rate since it can vary.

Why Founders Choose Legal Suvidha

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• One team for the whole journey — start, launch, post-launch and every annual filing after.
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