GST Filing Calendar 2025-26: Every Deadline You Need to Know

Missing a GST deadline is not just an administrative inconvenience. It triggers late fees, interest charges on unpaid tax, blocked Input Tax Credit claims, and in repeated cases, suo-moto cancellation of your GST registration. For CA firms managing dozens of clients and for businesses handling their own filings, keeping track of every due date across the financial year is essential.

This is your complete GST filing calendar for FY 2025-26 (April 2025 to March 2026), covering all monthly, quarterly, and annual return deadlines.

Monthly Filings: GSTR-1 and GSTR-3B

Every regular taxpayer with aggregate turnover above ₹5 crore must file GSTR-1 (outward supply details) and GSTR-3B (summary return with tax payment) on a monthly basis. The due dates follow a consistent pattern throughout the year.

GSTR-1 reports all outward supplies (sales invoices, credit notes, debit notes) and is due on the 11th of the following month. GSTR-3B is the summary return where you declare your output tax liability, claim ITC, and pay the net tax due. It is filed by the 20th of the following month.

Quarterly Filings

Businesses under the QRMP scheme file GSTR-1 and GSTR-3B quarterly instead of monthly. The quarterly due dates for FY 2025-26 are:

*GSTR-3B quarterly due date varies by state: 22nd for taxpayers in Category A states (such as Maharashtra, Gujarat, Karnataka, Tamil Nadu) and 24th for Category B states (remaining states and UTs).

Invoice Furnishing Facility (IFF)

QRMP taxpayers can optionally upload B2B invoice details for the first two months of each quarter using the Invoice Furnishing Facility. IFF is due by the 13th of the following month and allows your buyers to claim ITC without waiting for your quarterly GSTR-1.

Composition Dealers: CMP-08

Taxpayers registered under the composition scheme must file CMP-08 (statement-cum-challan) quarterly by the 18th of the month following each quarter. The annual return GSTR-4 is due by April 30th of the following year.

Annual Filings

Annual returns are where many businesses and CA firms face the most pressure, since they require reconciliation of the entire year's data.

• GSTR-9 (Annual Return): Due by 31 December 2026 for FY 2025-26. Required for all regular taxpayers. This return consolidates all monthly or quarterly returns into a single annual summary with turnover, tax paid, ITC claimed, and demand/refund details.
• GSTR-9C (Reconciliation Statement): Due by 31 December 2026 for FY 2025-26. Required for taxpayers with aggregate turnover exceeding ₹5 crore. GSTR-9C is a self-certified reconciliation between the audited financial statements and the GSTR-9 figures.

Key Tips to Never Miss a Deadline

Staying on top of GST deadlines requires more than a wall calendar. Here are practical steps that the most efficient firms and businesses follow:

• Set 30-day advance reminders: For each due date, create a reminder 30 days in advance. This gives your team enough lead time to collect data, reconcile differences, and prepare the return without last-minute scrambling.
• Use a compliance calendar tool: Spreadsheets and manual tracking break down as client counts grow. A dedicated compliance management tool that tracks deadlines across all clients, sends automated reminders, and flags overdue filings is essential for firms managing more than a handful of GSTINs.
• Reconcile monthly, not annually: The single biggest cause of GSTR-9 delays is waiting until December to reconcile twelve months of data. Instead, reconcile GSTR-2B with your purchase register every month. Fix mismatches in real-time when the data is still fresh and vendors are still responsive.
• Keep GSTR-2B reconciliation current: Your ITC claims in GSTR-3B should match what appears in GSTR-2B. Any differences need to be tracked and resolved monthly. Unreconciled ITC creates problems at annual return time and during audits.
• File nil returns on time: Even if you have no transactions in a period, nil returns must still be filed by the due date. The late fee for nil returns is ₹20 per day, and missing two consecutive returns triggers ITC blocking.

What Happens If You Miss a Deadline

The consequences of late filing are concrete and cumulative:

• Late fee: ₹50 per day (₹25 CGST + ₹25 SGST) for regular returns, subject to a cap based on turnover. For nil returns, the late fee is ₹20 per day (₹10 CGST + ₹10 SGST).
• Interest on tax liability: Interest at 18% per annum is charged on the outstanding tax amount from the due date until the date of payment. This is calculated on a daily basis and adds up quickly on larger liabilities.
• ITC blocking: If you fail to file GSTR-3B for two or more consecutive tax periods, your ability to file GSTR-1 is blocked. This means your buyers also cannot claim ITC on your invoices, damaging your business relationships.
• Suo-moto cancellation: Persistent non-filing can lead to the tax officer initiating suo-moto cancellation of your GST registration. Reviving a cancelled registration requires an application within 30 days and is subject to officer approval.

The cost of non-compliance compounds. A single missed deadline might cost a few hundred rupees in late fees. A pattern of missed deadlines can disrupt your entire input tax credit chain, alienate customers, and put your registration at risk.