As per my knowledge, your CTC is ₹4,20,000, and in this, ₹2,00,000 is exempted. Now you're left with ₹2,20,000. Under section 80C, you can show savings of ₹1,00,000. Now you're left with ₹1,20,000. As you fall under category A (i.e., 10% tax would be deducted on this), so ₹1,20,000 * 10/100 = ₹12,000 per annum. Per month, ₹1,000 would be deducted every month.