All GST Registered business have to file monthly or quarterly GST returns and an annual GST return based on the type of business. These GSTR filings are done online on the GST portal

A GST return is a document containing details of all income/sales and/or expenses/purchases that a GST-registered taxpayer is required to file with the tax administrative authorities. This is used by tax authorities to calculate net tax liability.

Under GST, a registered dealer has to file GST returns that broadly include:

Purchases
Sales
Output GST (On Sales)
Input GST (GST paid on purchases)
https://taxring.com/service/file-gst-return