Rather than multiplying deductions by an assumed slab rate, the calculator computes your actual tax twice — once with no deductions and once after claiming them — and reports the difference. That handles slab boundaries correctly, which a flat multiplication does not.

Every deduction is capped at its statutory ceiling first, so entering ₹3 lakh under 80C still counts only ₹1.5 lakh. The headroom figure shows how much of each cap you have left.

These deductions apply under the old tax regime. The new regime allows very few of them, so compare both regimes before deciding.

Given: Salaried, income ₹12,00,000, 80C ₹1,50,000, NPS ₹50,000, 80D ₹25,000

Total eligible deductions = ₹2,25,000  ·  Standard deduction ₹50,000 applies in both cases

Without deductions: taxable ₹11,50,000 → tax ₹1,57,500 + cess = ₹1,63,800

With deductions: taxable ₹9,25,000 → tax ₹97,500 + cess = ₹1,01,400

Tax saved ≈ ₹62,400 — an effective 27.7% return on the amount invested.

• These deductions are available under the old regime only; the new regime permits almost none of them.
• 80D limits vary by age — ₹25,000 for self and family under 60, up to ₹1,00,000 including senior citizen parents.
• Section 24(b)'s ₹2,00,000 cap applies to a self-occupied property; let-out property rules differ.
• 80CCD(1B) is over and above the 80C limit, which is why it is entered separately here.
• Surcharge and marginal relief for very high incomes are not applied.

Do these deductions work in the new regime?
Mostly no — the new regime trades deductions for lower slab rates. Compare both before choosing.

What counts under 80C?
EPF, PPF, ELSS, life insurance premium, principal on a home loan, tuition fees, NSC and five-year tax-saver FDs.

Is NPS separate from 80C?
Yes — 80CCD(1B) gives an extra ₹50,000 over and above the ₹1.5 lakh 80C ceiling.