India gives every individual taxpayer a choice of two ways to compute income tax. The new regime (the default since FY 2023-24) has low, wide slab rates and almost no deductions. The old regime has higher rates but lets you subtract a long list of investments and expenses - 80C, 80D, HRA, home-loan interest - before tax is applied. The regime that leaves you with more money depends entirely on how much you would be able to deduct, which is why this calculator computes both side by side rather than asking you to guess.
Three things sit on top of the slabs
- Standard deduction of ₹75,000 is subtracted from salary before the slabs apply (₹50,000 in the old regime). No proof, no investment.
- Section 87A rebate cancels the entire tax if taxable income is ₹12,00,000 or less - so a salary of up to ₹12,75,000 is tax-free - with marginal relief just past the limit so a ₹1 raise cannot cost you ₹60,000.
- 4% health and education cess is added to whatever tax remains. Above ₹50 lakh of taxable income a surcharge applies too - capped at 25% in the new regime, 37% in the old.
What the old regime lets you deduct
The old regime keeps the pre-2020 slabs (nil to ₹2.5 lakh, 5% to ₹5 lakh, 20% to ₹10 lakh, 30% above) but allows the deductions most people associate with "tax saving": up to ₹1.5 lakh under Section 80C, ₹25,000-₹1,00,000 under 80D for health insurance, ₹50,000 extra for NPS under 80CCD(1B), up to ₹2 lakh of home-loan interest, and the HRA exemption for people who pay rent. Stack enough of these and the old regime's higher rates are applied to a much smaller number. The calculator's break-even deduction tells you exactly how much you would need before that happens - and for most salaried people since 2025, the honest answer is "more than you have".
How to use it
Enter your gross annual salary (the CTC figure from your offer letter, minus employer PF if it is included there), then add any deductions you actually have under the old regime - the calculator will not assume any. Add other income if you have it. The summary shows tax under both regimes, the monthly in-hand under each, the slab-by-slab breakdown, and which regime saves more. Every rule applied - the rebate, marginal relief, surcharge relief, cess rounding - is listed on the how we calculate page, and the figures are checked against a hand-verified test suite before each release. Nothing you type leaves your browser.