GSTR 9C is a statement of reconciliation between the Annual returns filed in GSTR 9 for a financial year and the figures as per the audited annual Financial Statements of the taxpayer. The GSTR-9C must be filed on or before 31st December of the subsequent year.
If GST returns are not filed within the specified time limits, you will be liable to pay interest and a late fee.
Interest is charged at 18% per annum. It has to be calculated by the taxpayer on the amount of outstanding tax to be paid. The time period will be from the next day of filing to the date of payment.