How it works
The new regime is the default. It taxes salary after a ₹75,000 standard deduction, with nil tax up to ₹4 lakh and a rebate that can bring tax to zero when taxable income is up to ₹12 lakh. The old regime uses a ₹50,000 standard deduction, the 5%, 20%, and 30% slabs, and any extra deductions you type, such as 80C or HRA exemption. Both results add 4% health and education cess. Surcharge above ₹50 lakh is not calculated. This is not a substitute for the income-tax utility.
Tax payable = slab tax − rebate, then × 1.04 cess. New-regime marginal relief caps tax at the income above ₹12 lakh.