What is the GSTR-9C due date? The due date for filing the annual returns in GSTR-9 is the same deadline for GSTR-9C submission. Hence, the GSTR-9C must be deposited on or before 31st December of the year after the relevant FY under audit. The due date can be extended through the Government if deemed significant. Read more at FinacBookshttps://www.finacbooks.com/gst-return-filing/gstr-9c