taxer

universal tax calculator javascript library to calculate all kinds of taxes through out the world.

Library Architecture

It's designed with plugin mechanism and minimalist in mind. By default:

const taxer = new Taxer();
taxer.use(new CustomCalctor());
const taxInfo = taxer.calc(countryCode, income, options);

in which:

CustomCalctor should be a class implements Calctor interface which has:

• isMatched(countryCode, taxableIncome, options) method: to be hooked up if it is the first to return true.
• calc(taxableIncome, options) method: the taxInfo is calculated and returned.

If no matched calculator, an error will be thrown.

For example:

export class VnCalctor {
    constructor() {
    }

    calc(taxableIncome, options={}) {
        return {
            taxableIncome: taxableIncome
        }
    }

    isMatched(countryCode, income, options) {
        if (typeof countryCode === 'string') {
            countryCode = countryCode.toLowerCase();
        }
        return ['vn', 'vnm', 704, 'vietnam', 'viet nam'].indexOf(countryCode) > -1;
    }
}

That's how the library architecture works.

How to use

1. Configure

   1.1. From the default taxer with built-in tax calculators:

   const taxer = defaultTaxer();
   // add more custom calculator
   taxer.use(new CustomCalctor(options));

   1.2. From scratch

   const taxer = new Taxer();
   taxer.use(VnCalctor());
   taxer.use(UsaCalctor());
   taxer.use(SgCalctor());
   taxer.use(CustomCalctor(options));

2. Use

const taxInfo = taxer.calc(countryCode, income, options);
console.log(taxInfo);

How to develop

This is the minimalist plugin architecture inspired by express.js and koa.js a lot. Let's keep it as minimal and lightweight as possible.

Clone this repository and:

$ npm install
$ npm run test

Or with Docker:

$ docker-compose up

How to contribute

By writing custom tax plugins to create a good solid universal tax system throughout the world.

Follow Teracy workflow: http://dev.teracy.org/docs/workflow.html

References

These are related similar projects we should take a look:

• https://github.com/rkh/income-tax

• https://www.npmjs.com/package/uk-income-tax

License

MIT license. See LICENSE file.