The three-number formula, always the LOWEST: Basic ₹40,000/month. HRA received ₹18,000/month. Rent paid ₹20,000/month. City: Bengaluru (NON-METRO = 40%). (a) Actual HRA = ₹18,000. (b) Rent − 10% basic = ₹20,000 − ₹4,000 = ₹16,000. (c) 40% of basic = ₹16,000. Minimum = ₹16,000/month × 12 = ₹1,92,000/year exempt. Balance HRA (₹18K − ₹16K = ₹2K/month = ₹24K/year) is taxable. Metro cities, ONLY FOUR: Delhi (includes NCR, Gurgaon, Noida? ONLY Delhi proper = metro). Mumbai. Chennai. Kolkata. That is ALL. Bengaluru: NON-METRO (40%). Hyderabad: NON-METRO (40%). Pune: NON-METRO (40%). Ahmedabad: NON-METRO (40%). Jaipur: NON-METRO. Lucknow: NON-METRO. This is a very common error, tech employees in Bengaluru routinely claim 50% thinking Bengaluru is metro. Wrong. HRA when renting from parents: CBDT has allowed HRA exemption when rent is paid to parents who own the property.