GSTR-3B Due Date: Outward Supplies, ITC and Net Tax Payable for August 2026

Taxpayers filing GST returns on a monthly basis should take note of the upcoming GSTR-3B compliance for August 2026. The due date for filing Form GSTR-3B for August 2026 is 20 September 2026 for monthly filers. The GST Portal confirms that monthly GSTR-3B is generally due on the 20th day of the month following the relevant tax period.

What is Form GSTR-3B?

Form GSTR-3B is a summary GST return through which taxpayers report their GST liabilities and discharge the tax payable for the relevant tax period. Normal and casual taxpayers required to file GSTR-3B must furnish the applicable return for each tax period.

Section 39 of the Central Goods and Services Tax Act, 2017 covers furnishing of returns containing details such as inward and outward supplies, input tax credit (ITC) availed, tax payable and tax paid.

For August 2026, the monthly GSTR-3B compliance includes reporting and reviewing:

• Outward taxable supplies and the corresponding GST liability
• Inward supplies liable to tax under reverse charge, where applicable
• Eligible Input Tax Credit (ITC)
• ITC reversals and ineligible ITC, as applicable
• Exempt, nil-rated and non-GST inward supplies, where required
• Payment of net GST liability after utilisation of eligible ITC

Who Needs to File Monthly GSTR-3B?

The Quarterly Return Monthly Payment (QRMP) Scheme is available to eligible registered persons having aggregate turnover of up to Rs. 5 crore in the preceding financial year, subject to the prescribed conditions.

Notification No. 84/2020-Central Tax dated 10 November 2020 introduced the quarterly-return framework for eligible taxpayers from January 2021. Rule 61A of the CGST Rules prescribes the manner of opting for quarterly filing. A taxpayer whose aggregate turnover exceeds Rs. 5 crore during the current financial year is required to move to monthly filing from the first month of the quarter succeeding the quarter in which the threshold is crossed.

Accordingly, taxpayers with turnover exceeding Rs. 5 crore, as well as eligible taxpayers who have chosen monthly filing instead of QRMP, generally continue filing GSTR-3B every month.

Important Clarification for July–September 2026

The due date of 20 September 2026 relates specifically to the GSTR-3B for August 2026 for monthly filers; it is not the quarterly GSTR-3B due date for the entire July–September 2026 quarter. Current compliance calendars also identify GSTR-3B for August 2026 as due on 20 September 2026.

Taxpayers who have validly opted for QRMP follow the quarterly GSTR-3B filing cycle, with the GST Portal stating that quarterly GSTR-3B returns are generally due on the 22nd or 24th day of the month following the quarter, depending on the State or Union Territory.

What Should Taxpayers Check Before Filing?

Businesses should reconcile their sales records, GSTR-1 data, purchase records and available ITC before submitting GSTR-3B. Particular attention should be given to differences in outward tax liability, ITC eligibility, reverse-charge transactions and tax already deposited in the electronic cash ledger.

Accurate reconciliation before filing can help reduce errors, incorrect ITC claims and unnecessary interest or other compliance consequences.

Conclusion

Monthly GSTR-3B filers should ensure that their August 2026 return is accurately prepared and filed by 20 September 2026. Businesses should also verify their applicable filing frequency on the GST Portal rather than treating the July–September quarter description as a quarterly due date for all taxpayers.