Form GSTR-9 is an annual return to be filed once for each financial year by the taxpayers registered under GST, who were regular taxpayers, including SEZ units and SEZ developers.
When you required to file GST Annual Return (GSTR 9)?
An annual return required to be filed when a taxpayer having turnover more than 2 Crore in a financial year.
When you required to file GST Audit (GSTR 9C)?
An GST audit required to be filed when a taxpayer having turnover more than 5 Crore in a financial year.
Yes, to check that the taxpayer has assessed it correctly, an audit under GST is required. As of now GST audit if applicable to the dealer having turnover more than 5 Crore.
There may be general penalty for non filing of GST audit. As per the GST Act, due date of audit and annual return is specified as 31 st  December of subsequent fiscal year and in case of failure in complying with the same then as per act no specific penalty is prescribed. So, it will be covered under the head of general penalty of Rs. 25000.