Extension of GSTR-3B for September month/quarter till 25th October 2025: CBIC has extended the due date for filing GSTR-3B returns for both monthly and quarterly filers. It specifies that registered persons required to furnish returns under Section 39(1) i.e. monthly filers, may now submit their GSTR-3B for September 2025 up to 25th October 2025. Similarly, those covered under the proviso to Section 39(1) i.e., quarterly return filers under the July–September 2025 quarter, have been granted the same extended deadline of 25th October 2025.