Taxpayers missing the July 31 ITR filing deadline may face multiple penalties. These include a late-filing fee of up to ₹5,000 (₹1,000 if total income doesn't exceed ₹5 lakh), a revised return penalty of up to ₹5,000, and a penalty of 50%-200% for under-reporting income. Violating cash transaction rules can also attract a penalty equal to the amount received.