Understanding Income Tax Slabs in India

India uses a slab system — different portions of your income are taxed at different rates, rather than one flat rate on your entire income. Higher income doesn't mean your whole salary is taxed at the top rate; only the portion within each slab is. This is a progressive system: each slab of income is taxed at its own rate, and you can choose between the Old Regime (more deductions) and the New Regime (lower rates) each financial year, whichever works out cheaper for you.

Law update: The Income-tax Act, 2025 replaced the 1961 Act from 1 April 2026 — the terms "Previous Year" and "Assessment Year" are now merged into a single "Tax Year" concept, and section numbers have been renumbered. Slab rates and deduction rules themselves are unchanged. See the full guide to what changed under the New Income Tax Act pillar for details.

How "Only the Slab Portion" Actually Works

Imagine slabs are like buckets stacked on top of each other. Your income fills the first bucket completely before spilling into the next — and each bucket has its own tax rate. Only the amount that lands in a higher bucket gets taxed at that bucket's rate.

This matters more than it sounds: a ₹1 lakh raise that pushes you into a higher slab does NOT mean your entire income now gets taxed at that higher rate — only that extra ₹1 lakh does. This is exactly why two people with different total incomes, both partly in the same slab, don't end up paying wildly different effective tax rates — the lower slabs are taxed identically for both of them.

Old Regime vs New Regime

Feature	Old Regime	New Regime
Slab rates	Higher	Lower
Deductions (80C, HRA, etc.)	Allowed	Mostly not allowed
Filing complexity	More paperwork to claim deductions	Simpler
Best suited for	Large deduction claims (home loan, 80C, HRA)	Few or no deductions claimed

There's no universal "better" regime — it depends entirely on how much you claim in deductions. Run the numbers under both before filing each year, rather than assuming last year's choice still holds, since your deduction eligibility can change year to year. The New Regime section (115BAC under the old Act) has been renumbered under the Income-tax Act, 2025 but remains the default regime, with the rates unaffected by the renumbering.

A Worked Example: Calculating Tax Across Slabs

Say a salaried individual has a taxable income of ₹12 lakh under the New Regime. Rather than the entire ₹12 lakh being taxed at one rate, the amount is split across each slab in turn — the portion up to the first threshold is taxed at the lowest rate, the next slice at the next rate, and so on, until the full ₹12 lakh has been accounted for. Only the last slice — the amount actually falling in the highest slab this income reaches — is taxed at that top rate.

For example: if the applicable slabs tax the first ₹4 lakh at 0%, the next ₹4 lakh at 5%, and the remaining ₹4 lakh at 10%, only that final ₹4 lakh portion is taxed at 10% — not the full ₹12 lakh. The blended, effective tax rate on the whole income ends up meaningfully lower than the top slab rate this income touches.

Surcharge and Cess: The Extra Layers

Slab rates aren't the whole story for very high earners. Two additional charges sit on top of the basic tax calculated from the slabs:

Surcharge: An additional charge on the tax itself (not on income), applying only above certain high-income thresholds — it rises in steps as income increases further.
Health & Education Cess: A flat 4% charge on the tax plus surcharge, applicable to every taxpayer regardless of income level.

For most middle-income taxpayers, surcharge doesn't apply at all — it only kicks in well above the top slab threshold. Cess, however, applies to everyone, which is why the actual tax paid always ends up slightly higher than what the slab rates alone would suggest.

Why Knowing Your Slab Actually Helps

Estimating a bonus's real value: Knowing your marginal slab rate tells you exactly how much of a bonus or hike actually lands in your pocket versus going to tax.
Deciding if deductions are worth it: If your marginal rate is low, the paperwork for claiming deductions (only under Old Regime) may not be worth the effort compared to the New Regime's simplicity.
Timing income and investments: Knowing which slab you're in helps decide whether to book a capital gain this financial year or the next, or whether to accelerate or defer a bonus where you have any control over timing.
Comparing job offers accurately: A CTC comparison between two job offers is misleading without factoring in the marginal tax rate on the difference — a higher gross offer doesn't always translate to a proportionally higher take-home.

Common Mistakes to Avoid

Assuming a raise pushes your whole income into a higher rate: Only the incremental income above the previous slab threshold gets taxed at the new rate — the rest continues being taxed exactly as before.
Picking a regime once and never revisiting it: Since deduction eligibility and income can change year to year, the cheaper regime for you can also change — it's worth recalculating both regimes each year rather than defaulting to last year's choice.
Forgetting cess when estimating tax liability: A quick mental calculation using only slab rates will understate actual tax owed by the 4% cess that applies on top.
Confusing marginal rate with effective rate: Your marginal rate (the rate on your next rupee) is usually higher than your effective rate (total tax divided by total income) — using the marginal rate to estimate your overall tax burden overstates it.

Key Takeaway: Only the income within each slab is taxed at that slab's rate — not your entire income. You can choose between the Old and New tax regimes each year, whichever is cheaper for you, and deductions like 80C only apply under the Old Regime. Remember that cess (4%) applies to everyone on top of the calculated tax, and surcharge kicks in only for very high earners — both add to the final bill beyond the headline slab rate.

Frequently Asked Questions

What is a "marginal tax rate"?

It's the tax rate applied to your next rupee of income — the rate of the highest slab you currently fall into. It's different from your "effective" tax rate, which is your total tax divided by total income, and is usually lower than your marginal rate.

Can I switch tax regimes every year?

Salaried individuals with no business income can typically switch between Old and New regime every financial year when filing. Those with business or professional income face some restrictions on how often they can switch back.

Is there a basic exemption limit where no tax is owed?

Yes — both regimes have a basic exemption limit below which no income tax is owed, and the New Regime additionally offers a rebate that can bring the effective tax to zero up to a higher income threshold. These limits are revised periodically, so check the current year's figures before estimating your liability.

Do freelancers and business owners use the same slabs?

The same slab rates generally apply, but freelancers and business owners often have additional considerations — like presumptive taxation schemes, advance tax obligations, and different rules around switching between tax regimes each year.

Does the New Regime apply automatically if I don't choose one?

Yes — the New Regime is the default option. If you want to be taxed under the Old Regime instead, you generally need to actively opt in while filing your return.

Who actually has to pay surcharge?

Surcharge only applies above specific high-income thresholds well beyond the top slab — the vast majority of taxpayers never encounter it, since it's designed to apply an extra layer of tax only on very high earners.