ITR-3 is an Income Tax Return form applicable to individuals and HUFs who earn income from business or profession, in addition to income from salary, house property, capital gains, and other sources. It is also used by professionals like doctors, chartered accountants, and lawyers running a proprietorship or partnership firm. Filing ITR-3 ensures compliance with the Income Tax Act, 1961, allows reporting of complex income structures, and enables claiming deductions under sections such as 80C, 80D, and 80G. Taxpayers must maintain proper books of accounts, financial statements, and tax audit reports if turnover exceeds prescribed limits. The form must be filed online through the Income Tax Department portal, and verification can be done via Aadhaar OTP, net banking, or submitting a signed ITR-V. Accurate and timely filing prevents penalties, facilitates tax refunds, and provides legal proof of income. Professional assistance is recommended to reconcile business and professional income, compute taxable profits, claim deductions, and file returns correctly, ensuring compliance and avoiding scrutiny by tax authorities.