The income-tax glossary, in plain English.

The rebate that makes small incomes tax-free. New regime (FY 2025-26): if your total income is ≤ ₹12,00,000, up to ₹60,000 of slab tax is wiped out — so up to ₹12.75L of salary is effectively tax-free after the ₹75k standard deduction. There's marginal relief just above ₹12L, and it never applies to special-rate capital gains. Old regime: ₹12,500 rebate if income ≤ ₹5,00,000.

The classic ₹1,50,000 deduction basket — old regime only. It covers EPF, PPF, ELSS mutual funds, life-insurance premiums, home-loan principal, children's tuition, NSC and more, all sharing one ₹1.5L cap. In the new regime this deduction doesn't exist, which is exactly why the regime comparison matters.

Health-insurance premium deduction (old regime): up to ₹25,000 for self/spouse/children (₹50,000 if you're 60+), PLUS up to ₹25,000 for parents (₹50,000 if they're senior citizens). A family insuring senior parents can deduct up to ₹1,00,000 a year.

Three layers: 80CCD(1) — your own NPS inside the ₹1.5L 80C cap. 80CCD(1B) — an EXTRA ₹50,000 for self NPS, old regime only. 80CCD(2) — your employer's NPS contribution, deductible in BOTH regimes: up to 10% of basic+DA (old) or 14% (new). Employer NPS is the only big deduction that survives the new regime.

Old regime only. The exempt part of your House Rent Allowance is the LEAST of: (a) HRA actually received, (b) rent paid minus 10% of basic+DA, (c) 50% of basic+DA in a metro (Delhi/Mumbai/Kolkata/Chennai) or 40% elsewhere. High rent + high basic = big exemption — often the single biggest reason the old regime wins.

Short-term capital gains on listed equity/equity mutual funds (held ≤ 12 months, STT paid) are taxed at a flat 20% since 23-Jul-2024. No deductions can offset them, and the 87A rebate doesn't cover them in the new regime. Other short-term gains (debt, property) are taxed at your slab rate.

Long-term gains on listed equity/equity MF (held > 12 months): the first ₹1,25,000 each year is tax-free, the rest is taxed at 12.5% without indexation. Pro move: harvest gains up to the exemption every year (sell and rebuy) so the tax-free allowance never goes to waste — TaxSense flags your unused headroom automatically.

If your tax after TDS is ≥ ₹10,000, you must pay in installments: 15% by 15 Jun, 45% by 15 Sep, 75% by 15 Dec, 100% by 15 Mar (presumptive taxpayers: everything by 15 Mar). Miss an installment and s.234C charges 1%/month on the shortfall; pay less than 90% by year-end and s.234B adds 1%/month from April. Resident seniors (60+) without business income are exempt. Check the Planner tab for your personal calendar.

A flat cut from salary/pension income, no proofs needed: ₹75,000 in the new regime, ₹50,000 in the old (FY 2025-26). It's automatic — TaxSense applies it before anything else.

An extra tax on the tax itself for high incomes: 10% above ₹50L, 15% above ₹1cr, 25% above ₹2cr, and 37% above ₹5cr (old regime; the new regime caps at 25%). Surcharge on equity capital-gains tax is capped at 15% regardless. Marginal relief stops a ₹1 raise from costing you lakhs.

A flat 4% added on top of your income tax plus surcharge. Everyone pays it; it's in every TaxSense number you see.

Two parallel tax systems. New (default): lower slab rates, ₹75k standard deduction, 87A makes ≤₹12L income tax-free — but almost no deductions. Old: higher rates but HRA, 80C, 80D, NPS and home-loan interest can slash taxable income. Rule of thumb: heavy rent + maxed deductions → old often wins; otherwise new. TaxSense computes both, always, and shows the exact difference.

ITR-1 (Sahaj): resident, income ≤ ₹50L, salary + one house property (+ equity LTCG within the ₹1.25L exemption, new from AY 2025-26). ITR-2: capital gains beyond that, two+ properties, or income > ₹50L. ITR-3: business/professional income with books. ITR-4 (Sugam): presumptive business income ≤ ₹50L. TaxSense picks yours automatically — see the Planner tab.

Your employer's annual TDS certificate, issued by mid-June. Part A shows tax deposited against your PAN; Part B breaks down salary and deductions. It's the fastest source for your exact gross salary and basic+DA — the two numbers TaxSense needs most.

The tax department's own record of your money: TDS, interest, dividends, share sales, big purchases. Download both from incometax.gov.in before filing and reconcile — mismatches between your return and AIS are the #1 cause of notices.

This is the automated 'we processed your return' message every filer gets. Three outcomes: no change (relax), refund (great), or a demand (compare their computation column with yours in the PDF — the mismatch is usually TDS credit or an arithmetic difference). You have 30 days to respond to a demand; agree and pay, or disagree online with reasons. It is NOT a scrutiny notice.

The department found something structurally wrong with your return (missing income schedule, wrong form for your income mix, unmatched TDS…). You get 15 days to fix it via e-Proceedings — miss the window and the return can be treated as never filed. Fixing usually means filing a corrected return online; the notice itself lists the exact defect code.

The department wants to adjust your current refund against an OLD outstanding demand. You get 21 days to agree or contest online. Contest it if the old demand is wrong (very common with legacy TDS mismatches) — respond via the e-filing portal under 'Response to Outstanding Demand'; don't just let the refund vanish.

The #1 cause of notices: your return says one thing, the department's data (AIS/26AS) says another — usually unreported FD interest, dividends, or share sales your broker reported. Fix: download AIS before filing, reconcile every line, and if a notice already arrived, file a revised/updated return including the missed income.

The serious one: the department believes income escaped assessment. Timelines and monetary thresholds apply (generally 3 years, extendable when escaped income is large). Do NOT respond casually — this is the point where a professional (CA) should draft the reply. TaxSense helps you prevent these by reconciling AIS before filing, not fight them after.

For FY 2025-26 (AY 2026-27) the usual due date is 31 July 2026 for non-audit filers. Miss it and s.234F charges ₹5,000 (₹1,000 if income ≤ ₹5L), you lose loss carry-forwards, and interest keeps running. File early — refunds also arrive faster.