Income Tax Calculator India (FY 2025-26): Old vs New Regime With Worked Examples

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Income tax planning in India is not only about finding the tax amount at the end of the year. For most people, the real decision is how salary, deductions, regime selection, and take-home cash flow fit together month by month. A practical calculator should therefore help you do more than one action: it should estimate salary tax, compare old and new regimes, and show how deductions change taxable income. This page is built with that exact goal.

The Indian tax framework for FY 2025-26 (AY 2026-27) uses slab-based marginal taxation. That means each slab of income is taxed at a different rate, not your full income at the top slab. Many taxpayers overestimate their liability because they assume crossing a slab pushes all income into the higher rate. The correct method is incremental and this calculator follows that approach. After base tax, cess is applied and eligible rebate logic is considered so the output reflects a realistic planning estimate.

You can use this page in three ways. First, salaried users can model standard deduction and old-regime items like 80C, 80D, NPS, HRA, and home-loan interest. Second, business users can estimate tax from net profit after costs and depreciation. Third, the comparison tab highlights which regime currently delivers lower tax and stronger take-home. Together these flows reduce guesswork before payroll planning, advance tax decisions, and investment allocation.

The core engine is slab-wise marginal computation. In simple terms, taxable income is split into ranges, and each range is multiplied by its own rate. For example, if a part of your income sits in a 5% band and the next part in a 10% band, the calculator applies those rates only to their respective portions. This is the only accurate way to estimate liability under either regime.

For salary-tax mode, gross annual salary is the starting point. Under the old regime, eligible deductions are applied based on common sections: 80C, 80D, NPS (80CCD 1B), HRA treatment, and home-loan interest. Under the new regime, deduction availability is different, so the calculator applies the configured standard-deduction logic for that regime and then computes taxable income accordingly. The taxable number is then fed into slab rules and cess is added.

Rebate treatment is important because it can materially change final outflow at lower-to-middle income levels. The calculator checks rebate eligibility after slab tax plus cess and reduces final payable tax where applicable. This sequencing matters: if rebate is modeled incorrectly, the final tax number can be off by thousands. That is why the output includes separate fields for base tax, cess, rebate, and final payable amount.

Business-tax mode follows a similar structure but starts from gross business income and subtracts operating expenses, depreciation, and other allowable values to arrive at taxable profit. Advance tax paid is then netted out to estimate balance payable. This is useful for cash-flow planning because many owners only look at annual P&L but not interim tax payments. Comparison mode then allows side-by-side old/new results so you can evaluate whether deduction-heavy or simplified filing paths are currently better.

Suppose a salaried user has annual salary of ₹12,00,000 and expects ₹1,50,000 under 80C, ₹25,000 under 80D, and ₹50,000 under NPS. In old-regime view, the calculator first adjusts salary by standard deduction and eligible deductions, then computes slab tax on remaining taxable income. Cess is added and rebate is checked where relevant. In new-regime view, the tool applies new-regime deduction treatment and runs slab math again.

Assume the model returns old-regime tax of about ₹X and new-regime tax of about ₹Y (numbers depend on final input mix). If old-regime tax is lower by ₹18,000, the comparison card marks old regime as better and also shows higher take-home amount. If future deduction plans reduce, you can rerun quickly and see whether the recommendation flips. This scenario-testing workflow is usually more useful than a one-time static estimate.

• Enter annual numbers consistently; avoid mixing monthly deductions with yearly salary.
• Use comparison mode before locking payroll declarations for the year.
• For HRA, maintain rent and allowance records; missing assumptions can skew old-regime output.
• Re-run calculation when income changes due to bonus, switch, or variable pay revision.
• Treat results as planning estimates and verify filing values with official documents.

Methodology is slab-first and regime-aware: compute taxable income, apply slab rates incrementally, add cess, then apply rebate eligibility. Business mode computes taxable profit from gross income minus selected expenses and deductions, then applies tax logic and advance-tax offset for balance payable estimate.

Assumptions: rates and regime rules in this app are modeled for FY 2025-26 / AY 2026-27 configuration. Special incomes, surcharge edge cases, and rare exemptions are intentionally simplified for planning use. For return filing, validate with official sources and professional advice where required.

Use the calculator below to switch between salary tax, business tax, and old-vs-new regime comparison.