Special GST filing procedure: composition-scheme taxpayers must follow quarterly CMP-08 payments and annual GSTR-4 return compliance. Notification requires taxpayers paying tax under the composition provisions or availing the specified notification to file quarterly self-assessed tax statements in FORM GST CMP-08 by the eighteenth day of the month following each quarter and an annual return in FORM GSTR-4 by the thirtieth day of April after the financial year; filing these forms within those timelines is deemed compliance with the Act for the period the benefit is availed.