easy-tax

An Indian income-tax calculator for FY 2025-26 (AY 2026-27). Enter what you earned, pick a regime, and see the tax broken down line by line — including the bits most calculators hide, like which slab your income actually filled, why your surcharge went down, and what the other regime would have cost you.

Built with React 19, TypeScript and Vite.

Getting started

yarn install
yarn dev

Command	What it does
yarn dev	Start the dev server with HMR
yarn build	Typecheck and build to dist/
yarn preview	Serve the production build locally
yarn lint	ESLint
yarn format	Format everything with Prettier
yarn format:check	Verify formatting without writing (for CI)
yarn sync:readme	Refresh the generated year fields below

Generated fields

Markdown cannot compute anything when GitHub renders it, so the two dated fields in this file are written in by scripts/sync-readme.mjs and committed. Each sits between HTML comment markers that are invisible once rendered:

Region	Source
tax-year	RATE_FINANCIAL_YEAR_START in src/utils/tax.ts
copyright	The current calendar year

The tax year deliberately follows the rates rather than the clock, so this file can never claim a year the calculator does not implement. CI runs yarn sync:readme:check and fails if either has drifted — including on 1 January, when the copyright year turns over. Run yarn sync:readme and commit.

Deployment

Pushing to main runs .github/workflows/deploy.yml, which lints, checks formatting, typechecks, builds, and publishes dist/ to GitHub Pages at https://biswasray.github.io/easy-tax/. Pull requests run the same checks without deploying.

Because a project site is served from a subpath, vite.config.ts builds with base: '/easy-tax/'. On a custom domain or a <user>.github.io repository, build with VITE_BASE=/ instead.

One-time setup: Settings → Pages → Source: GitHub Actions.

Releasing

A deploy only happens when the version has gone up. The build writes its package.json version into dist/version.json, and CI compares that against the copy already live at /easy-tax/version.json:

package.json	Live site	Result
1.0.1	1.0.0	Deploys
1.0.0	1.0.0	Builds and verifies, skips deploying
1.0.0	absent	Deploys — treated as a first release

So to ship a change, bump the version:

yarn version --new-version patch   # or minor / major

Pushes that do not bump the version still run the full lint, format and build checks and go green — they just don't publish. Because the comparison is against what is actually live rather than against the previous commit, a deploy that fails or is skipped is picked up again by the next run.

yarn.lock is not committed, so CI resolves dependency versions fresh on every run. A build can therefore pick up a new release of a dependency that was never built locally.

What it works out

All the logic lives in src/utils/tax.ts as a single pure function, calculateTax(data). It returns a full TaxCalculationResult rather than a bare number, so the UI can show its working.

Income

Input	Treatment
Salary	Slab rates, after the standard deduction
FD & savings interest, dividend, other income	Slab rates
Intraday trading	Speculative business income → slab rates
Equity & commodity F&O	Non-speculative business income → slab rates
Long-term capital gain	12.5% above the ₹1,25,000 exemption — s.112A
Short-term capital gain	20% — s.111A
Crypto & VDA gain	Flat 30%, no deductions, no exemption — s.115BBH

Deductions

Deduction	Limit	Regime
10(13A) — HRA	The least of three tests, below	Old
Standard deduction	₹75,000 new regime · ₹50,000 old regime	Both
Business expenses — s.37	Your business income	Both
80C	₹1,50,000	Old
80CCD(1B) — NPS	₹50,000, on top of 80C	Old
80D — self, spouse, children	₹25,000	Old
80D — parents	₹25,000, or ₹50,000 when they are 60 or older	Old
80E — education loan interest	No ceiling	Old
80G — donations at 100%	No qualifying limit	Old
80G — donations at 50%	10% of adjusted gross total income	Old
24(b) — home-loan interest	₹2,00,000	Old

Everything except the standard deduction and business expenses reduces slab income only; none of it can be set off against capital gains or crypto taxed at special rates. The two 80D sub-limits are separate, so unused self/family room cannot absorb an overspend on the parents' policy.

HRA is an exemption rather than a deduction, so it comes off salary before everything else, the standard deduction included. Rule 2A makes it the least of three figures: the HRA you were paid, 50% of basic salary in Delhi, Mumbai, Kolkata or Chennai (40% anywhere else), and the rent you paid over 10% of basic. "Salary" there means basic plus DA, not gross pay, which is why the form asks for basic separately — and why the HRA you enter is not added to your income again, since it is already inside the salary figure. The results panel names all three tests so you can see which one bound. Pay no rent and nothing is exempt, however much HRA your payslip shows.

80CCD(1B) is the extra ₹50,000 of NPS that section 80CCE leaves outside the ₹1,50,000 pool, so a maxed-out 80C does not eat into it. Employer contributions under 80CCD(2) — the one deduction the new regime does allow — are not modelled, because the ceiling depends on basic pay in ways the form does not capture.

80G models the two common categories. The 100% one — PM National Relief Fund, PM CARES, the National Defence Fund — is deductible in full. The 50% one covers registered trusts and NGOs: half of what you give is deductible, and only the part falling within 10% of your adjusted gross total income, which is slab income after the standard deduction, business expenses, the house-property loss and the other chapter VI-A deductions. Donations over ₹2,000 paid in cash do not qualify, and the calculator takes your word that they were not.

24(b) is the interest on a loan for the house you live in, not the principal — that belongs in 80C. It becomes a loss from house property and is set off against your other income. The ₹2,00,000 ceiling doubles as the section 71(3A) cap on that set-off, so one figure does for both. The new regime allows neither the deduction nor the set-off.

Expenses and GST

GST is not an income-tax deduction. Paying it on a phone bill or a restaurant meal does nothing for your income tax, and there is no field for it.

Where it counts is as a business cost. The GST charged on your brokerage — along with the brokerage itself, exchange and demat charges, data feeds and subscriptions — is an expense of earning intraday and F&O income, deductible under section 37. This one works under both regimes, because it is a cost of the business rather than a chapter VI-A deduction. Enter the total under Business expenses.

Two limits apply. Only GST you could not reclaim as input tax credit is a cost at all; if you are GST-registered and claimed the credit, leave it out. And the deduction stops at your business income, because a business loss cannot be set against salary (s.71(2A)) and losses are not modelled here — expenses beyond the income they belong to are dropped rather than carried anywhere.

And then

• Unused basic exemption set off against STCG first, then LTCG (STCG is taxed higher, so absorbing it first minimises the bill). Crypto is excluded, as s.115BBH requires.
• Rebate u/s 87A — ₹60,000 up to ₹12L of total income under the new regime, ₹12,500 up to ₹5L under the old. No rebate against LTCG or crypto, and none against 111A short-term gains under the new regime.
• Marginal relief u/s 87A once the new regime's ₹12L threshold is passed: the rebate is gone, but the tax payable is limited to the amount by which total income overshoots ₹12,00,000, so a raise can never cost more in tax than it added in income. Applied last, to the final bill including cess — total income of ₹12,50,000 pays ₹50,000, not ₹67,500 plus cess. It stops short of tax on capital gains and crypto, which section 87A cannot touch. The old regime has no equivalent: ₹5L is a hard cliff.
• Surcharge at 10/15/25% (plus 37% over ₹5cr in the old regime), with the 15% cap on the part attributable to 111A, 112A and dividend income.
• Marginal relief where crossing a surcharge threshold would otherwise cost more in tax than the extra income earned.
• 4% health and education cess, and rounding to the nearest ₹10 per s.288B.

Assumptions

The calculator is built for one taxpayer profile, and the rates are named constants at the top of src/utils/tax.ts so they are easy to bump each year.

RATE_FINANCIAL_YEAR_START in that file records which year those rates belong to, and the header labels itself from it — so the displayed FY and AY can never drift away from the rates in use. To roll the app forward, update the rates and that one constant together. Until then the app compares the constant against today's date and says plainly that the current year's rates are not in yet.

Other assumptions:

• Resident individual under 60 — no senior-citizen slabs.
• Deductions are limited to those listed above. LTA, 80CCD(2) employer NPS, 80TTA savings interest and 80GG rent are not modelled, so the old regime will look worse than it really is if you rely on them.
• Only a self-occupied house is modelled. Rent received, the 30% standard deduction against it and a let-out property's uncapped interest are not.
• Losses are not carried forward. A negative business or other-income figure sets off against other income within the same calculation only, with no speculative/non-speculative ring-fencing.

It is an estimate to help you compare regimes, not a filing tool. Check with a tax professional before you file.

Example

import { calculateTax } from './src/utils'

const result = calculateTax({
  taxRegime: 'old',
  salaryIncomeAnnually: 1000000,
  section80CAnnually: 150000,
  section80DSelfFamilyAnnually: 25000,
})

result.totalIncome // 775000
result.totalTaxPayable // 70200
result.deductions.section80C // { claimed: 150000, allowed: 150000, limit: 150000 }

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