The tax calculator that argues with itself before it ships.
NewRegimeTax is ours — we built it, we pay for it, and we give it away. It exists because most income-tax calculators in India quietly get one edge case wrong, and the people most likely to be hurt by it are the ones least able to check.
- What it is
- A free income-tax calculator for India, running entirely in the browser.
- What we built
- 3 calculators, 8 guides and 20 salary-by-salary breakdowns.
- The hard part
- Section 87A marginal relief, and proving it stays correct.
- Who paid for it
- We did. There is no client, no ads and no sign-up.
A cliff that isn't really a cliff.
What the rule says
Under the new regime, a taxable income of ₹12,00,000 attracts ₹60,000 of slab tax — and the Section 87A rebate wipes it out completely. You pay nothing. For a salaried person the ₹75,000 standard deduction means a ₹12,75,000 salary lands exactly there.
Where it goes wrong
Earn one rupee more and a naive calculator drops the rebate entirely, jumping your tax from zero to ₹61,500. That is not the law. Marginal relief caps the tax so it can never exceed the income above the threshold.
What it costs a person
At ₹12.10 lakh taxable the correct tax is roughly ₹10,000 plus cess. A calculator that ignores marginal relief shows ₹61,500 — a difference of about ₹51,500 on a salary where that matters enormously.
Why it stays broken
It only shows up in a narrow band just above a threshold. Nobody notices in casual testing, the number looks plausible, and the person seeing it usually has no way to know it is wrong.
We made the build fail rather than the number.
Getting marginal relief right once is not the hard part. Keeping it right through every Budget, every slab change and every refactor is. So the correctness lives in the build, not in someone remembering to check.
Hand-compute the truth
Known-correct figures worked out by hand: zero-tax cases, rebate edges, surcharge with marginal relief, HRA, presumptive business income, full deduction stacks.
Turn them into tests
Every one of those becomes an automated test, including the awkward bands either side of each threshold where the bugs actually live.
Block the release
If any figure drifts, the release does not ship. Not a warning, not a ticket — the build stops. A wrong tax number is worse than a late one.
Re-run every Budget
New slabs mean the whole suite runs again before anything is published, so a Budget update cannot quietly break last year's edge cases.
A calculator is the small part.
- 3 calculators — income tax, capital gains, and a rent-receipt generator for HRA claims.
- 8 written guides, from old-vs-new regime to the 80C deduction list.
- 20 salary breakdowns, one page each from ₹7 lakh to ₹60 lakh.
- A published methodology page setting out exactly how every figure is derived.
- Surcharge marginal relief at ₹50 lakh, ₹1 crore, ₹2 crore and ₹5 crore, plus 4% cess.
- No sign-up and no upload — the whole thing runs in your browser.
You are hiring the habit, not the calculator.
Nobody asked us to handle marginal relief. There was no client, no deadline and no one checking. We did it because shipping a number we knew could be wrong was not an option — and that is the same standard your project gets, whether it is a five-page website or a system your staff use every day.
Bring us the problem nobody else wants to look at.
If your business has a job that does not fit any product you can buy, that is the kind of thing we like. Tell us about it and we'll build you a free working demo before you commit to anything.
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