Income Tax Calculator: How It Works, Formula and a Worked Example

Estimate your income tax liability under Old vs New tax regimes for FY 2026-27. Here is the formula, a worked example, the mistakes to avoid, and a free calculator with a downloadable PDF report.

Abhishek sharma
Editorial Lead
Updated September 17, 2026
4 Min Read

Ask five people in India how this is calculated and you will get five confident answers, most of them slightly wrong. It is not their fault — the arithmetic is rarely explained, only the result is shown. So let us do it the other way round: first the logic, then the formula, then your own numbers in the income tax calculator.

Cover image slot — add a screenshot or illustration from Admin → Blog when it is ready.

Prefer to start with your own figures? Use the Income Tax Calculator now, or continue for the formula and a worked example.

The logic, in plain language

Calculates total tax based on slab-wise rates for the selected financial year.

The formula behind it:

Slab-based progressive taxation
Symbol What it means
IT Income Tax
Cess 4% Health & Education Cess

Nothing is rounded away quietly and nothing is assumed on your behalf. If a figure appears in the result, it came from something you entered.

Putting real figures through it

Annual salary of ₹10 Lakh assessed against slabs.

Change any one input and watch the result move — that sensitivity is the real lesson. It is far more useful than memorising a single outcome, because your own rate, tenure or contribution will never match the example exactly.

Using the Income Tax Calculator, step by step

  1. Open the Income Tax Calculator.
  2. Enter your figures. Use the ones on your statement, sanction letter or scheme document rather than a remembered number.
  3. Read the result card — the headline figure plus the breakdown that produced it.
  4. Adjust one input at a time to see what genuinely moves the outcome.
  5. Tap Download PDF to keep a copy of the calculation, with your inputs and assumptions printed on it.

The PDF takes a few seconds to build because it is a properly typeset report, not a screenshot. You will see a progress message while it is being prepared, and the download starts on its own.

Things worth knowing before you decide

  • Compare both regimes to find lower liability.
  • Keep investment proofs ready for Old Regime deductions.

Where people usually slip up

  • Forgetting to add health & education cess.

If you want to go a level deeper afterwards, read up on understanding tax regimes. Both come up the moment you start comparing options seriously.

Interactive calculator

Try the Income Tax Calculator

Enter your own figures below. The same calculator and PDF report remain available on the focused calculator page.

Total Income Tax

₹0

Gross Income

₹5,000

Net Deductions

₹2,25,000

Portfolio Mix

Deductions
Tax

Growth Curve

Tax Efficiency Insight

Based on your ₹5,000 income and ₹2,25,000 deductions, your total tax liability is estimated at ₹0 under the new regime.

Tax Slab Breakdown

Total Income Tax₹0
Health & Education Cess (4%)₹0
You invest ₹5,000 every month for 20 years. At an estimated 12% annual return, your total investment is ₹5,000 and the estimated total value is approximately ₹0. Around ₹2,25,000 represents estimated growth.

Next Architectural Steps

Open the full calculator

What else you will find on VIA Capital

The calculator is one corner of a much bigger free toolkit. While you are here:

New tools and sections go live regularly, and each one gets written up here the same way.

Questions people ask us

Is the Income Tax Calculator free to use? Yes. Every calculator on VIA Capital is free, works without a login, and nothing you type is stored on our servers.

How accurate is it? The arithmetic is exact — it is the formula shown above, nothing hidden. Accuracy of the answer depends on your inputs. Rates, tenures and charges change, so use the figures from your own statement or sanction letter rather than a number you remember.

Can I save or share the result? You can download a formatted PDF report of your calculation and share it with your family, your CA or your bank. The download link sits right under the result.

Does it work on a phone? It does. The income tax calculator is built mobile-first, which is how most people in India actually search for "tax".

Is this investment advice? No. VIA Capital is an education platform. We show you the maths and the assumptions; the decision, and the responsibility for it, stays with you. For anything personalised, speak to a SEBI-registered professional.

The short version

Estimate your income tax liability under Old vs New tax regimes for FY 2026-27. The formula is public, the assumptions are printed on the page, and the calculation is yours to keep as a PDF.

👉 Run your own numbers in the Income Tax Calculator

VIA Capital publishes financial education only. Nothing here is investment advice or a personalised recommendation, and no calculator output should be treated as a promise of returns.

Educational content only. Educational content only. Not investment advice or a personalised recommendation.

Written by

Abhishek sharma

Discussion (0)

Log in to join the conversation.

Sign In to Comment