README

Monthly TDS under the new or old regime using FY 2025-26 slabs.

Works out the tax to deduct from this month's salary by annualising the pay, taxing it properly, subtracting what has already been deducted, and spreading the balance over the months that remain.

One of the CRMLeaf payroll tools. The arithmetic and the dated statutory rate tables live in crmleaf/payroll-core; this package is the thin skin that makes one calculator installable, mountable and embeddable on its own.

Note

A wrong figure or an out-of-date rate is almost always a payroll-core matter, since that is where the tables live. Anything about this tool's routes, views or browser asset belongs here.

Install

Composer - Laravel auto-discovers the service provider, so this is the whole setup:

composer require crmleaf/tds-calculator

npm - the same calculation, re-exported from @crmleaf/payroll-js so you can install this one tool and nothing else:

npm install @crmleaf/tds-calculator

Note

Not on npm yet. The script-tag route below needs no registry and works today. Installing this package straight from git will not resolve @crmleaf/payroll-js, which is not published yet either.

A plain script tag - no build step, no bundler, no server. Build the browser bundle once and serve the file yourself:

<script src="/js/payroll.min.js"></script>
<script>
const result = CrmleafPayroll.tds({ monthlyGross: 100000, regime: "new" });
console.log(result.explain);
</script>

payroll.min.js is the single-file browser build. Get it by running npm run build in @crmleaf/payroll-js and copying dist/payroll.min.js into whatever your site serves as static assets.

A hosted CDN build is coming soon, which will reduce this to a single URL. Serving the file yourself works today and keeps working afterwards - it is the only option that needs no third-party request, so plenty of projects will want to stay on it.

See it working first

demo/index.html in this repository is a working copy of TDS Calculator in one file: the form, the calculation and the working, with no build step and no server. Drop payroll.min.js beside it and open it from disk.

cp /path/to/payroll-js/dist/payroll.min.js demo/
open demo/index.html

Nothing on that page reaches the network, which is the point: it is a calculator people paste salary figures into.

Use it

Plain PHP, no framework and no container:

use Crmleaf\Payroll\Calculators\TdsCalculator;
use Crmleaf\Payroll\Money;

$result = (new TdsCalculator())->calculate(
    monthlyGross: Money::fromRupees(100_000),
    regime: 'new',
);

echo $result->explain();      // the formula with the real operands in it
echo $result->workings();     // every step, one per line, with its citation
print_r($result->toArray());  // snake_case, ready for JSON

Laravel - resolve it from the container, or type-hint it anywhere:

use Crmleaf\Payroll\Calculators\TdsCalculator;

public function show(TdsCalculator $calculator)
{
    return $calculator->calculate(
        monthlyGross: Money::fromRupees(100_000),
        regime: 'new',
    )->toArray();
}

Blade - one component, no controller:

<x-crmleaf::tds-calculator />

HTTP - off by default. Publish the config and turn the route on:

php artisan vendor:publish --tag=tds-calculator-config

// config/tds-calculator.php
'route' => ['enabled' => true, 'prefix' => 'tools'],

curl -X POST https://example.test/tools/tds-calculator \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json' \
  -d '{"monthly_gross":100000,"regime":"new"}'

The JSON response carries the figures, the working and the statutory citations:

{
  "tool": "tds-calculator",
  "data": { "…": "every figure, snake_case, with a *_formatted twin" },
  "explain": "the formula with the real operands substituted",
  "working": [{ "label": "…", "amount": 0, "formula": "…", "citation": "…" }],
  "citations": ["…"]
}

JavaScript:

import { tds } from '@crmleaf/tds-calculator';

const result = tds({ monthlyGross: 100000, regime: "new" });

No server needed

The maths here is arithmetic over versioned rate tables, so it runs anywhere. The published asset binds the markup and computes in the browser:

php artisan vendor:publish --tag=tds-calculator-assets

<section data-crmleaf-tool="tds-calculator">
  <form data-crmleaf-form> … </form>
  <div data-crmleaf-output hidden></div>
</section>

<script src="/js/payroll.min.js"></script>
<script src="/vendor/tds-calculator/tds-calculator.js"></script>

If the browser build is absent the script does nothing and the form posts to the server instead, so the page works either way.

Inputs

Field	Type	Required	Default	Notes
`monthly_gross`	money (₹)	Yes	`100000`
`regime`	one of `new`, `old`	No	`"new"`
`age`	integer	No	`30`	Only the old regime varies the exemption limit by age.
`deductions`	array or JSON	No	-	Keyed by section: 80c, 80ccd_1b, 80d_self_below_60, 80tta, 80ttb, 24b_self_occupied, 80ccd_2. Amounts in rupees.
`months_remaining`	integer	No	`12`
`tax_already_deducted`	money (₹)	No	`0`
`as_of`	date (YYYY-MM-DD)	No	-	Set this to recompute a prior year on that year's slabs.

Optional fields you leave out are omitted from the call entirely, so the calculator's own documented defaults apply.

Every figure here rests on a statutory rate, so the call takes as_of. Set it and the calculation runs on the rates in force on that date, which is what makes a prior year recomputable rather than merely rememberable.

Statutory basis

Income-tax Act 1961, section 192 read with section 115BAC, on the FY 2025-26 slabs given by the Finance Act 2025, including the section 87A rebate with its marginal relief and section 288B rounding.

Rates are data, not code: they live in dated tables with a cited source in crmleaf/payroll-core, so a rate change is a new dated entry rather than an edit to a constant.

Important

This package implements our reading of the applicable statutes and is provided without warranty. It is a calculation library, not tax advice. Verify against your own compliance obligations before relying on the output for statutory filing.

Publishing

Tag	Publishes
`tds-calculator-config`	`config/tds-calculator.php`
`tds-calculator-views`	`resources/views/vendor/tds-calculator`
`tds-calculator-assets`	`public/vendor/tds-calculator`

crmleaf / tds-calculator

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