The August 31 deadline applies to ITR-3 and ITR-4 filers who aren't liable for a tax audit. It covers freelancers, independent professionals, consultants, small business owners, intraday and F&O traders, and taxpayers eligible for presumptive taxation scheme under Sections 44AD, 44ADA and 44AE. Salaried people earning additional freelance, F&O or intraday trading income must file by the deadline.