GST filing is a mandatory process for every GST-registered business in India. It involves submitting regular returns to the government that show details of sales, purchases, tax collected, and input tax credit claimed. Key returns include GSTR-1 (due on the 11th of the next month) for outward supplies and GSTR-3B (due on the 20th of the next month or as per the turnover-based schedule) for monthly tax summary. The annual return GSTR-9 is due by 31st December of the following financial year. Timely and accurate filing helps avoid penalties, ensures compliance, and allows businesses to claim input tax credit properly. Late filing attracts interest and late fees. Proper GST filing is essential for smooth business operations and maintaining trust with tax authorities.