It states that 31 July was the due date for taxpayers filing ITR-1 and ITR-2, while 31 August is the due date for non-audit business and professional taxpayers filing ITR-3, ITR-4 and ITR-5. 31st August is the due date for business and professional taxpayers filing ITR-3, ITR-4, and ITR-5 provided their accounts do not require a tax audit. Arjuna (Fictional Character): Krishna, but ITR-3 and ITR-5 are also filed by big businesses whose accounts are audited. Krishna (Fictional Character): Arjuna, tax audit applies mainly in three situations:Business: where total turnover or sales in the year crosses ₹1 crore, tax audit becomes compulsory. It belongs to the non-audit business and professional taxpayers filing ITR-3, ITR-4, and ITR-5.