TaxJs

TaxJs is a typescript and javascript library to calculate german tax.

The code is generated from pseudo code from https://www.bmf-steuerrechner.de/

Test page: https://taxcalcs.github.io/taxjs-test/

Usage

let tax = new Lohnsteuer2021Big();
tax.initInputs();

tax.setLZZ(2); // Lohnzahlungszeitraum
tax.setKVZ(1.3); // Einkommensbezogener Zusatzbeitragssatz
tax.setSTKL(1); // Steuerklasse
tax.setPVZ(1); // Zuschlag soziale Pflegeversicherung
tax.setRE4(new Big(1234500)); // Steuerpflichtiger Arbeitslohn in Cent

tax.calculate();

tax.getLSTLZZ().toNumber(); // Lohnsteuer in Cent

You can find all fields on the test page.

Dependencies

As replacement for the Java BigDecimal class the library big.js and the typescript definition @types/big.js are used.

Development

For convert xslt file into xslt sef file you have to install xslt3.

npm install -g  xslt3

and

npm run compile-xsl

For compile typscript into javascript you have to install typescript.

npm install -g  typescript

How to integrate and generate updated tax calculation from pseudo code

1. Download the new XML file from https://www.bmf-steuerrechner.de/ and save it to build/unpacked/.
   • Attention: Files should end with Big after the filename, so Lohnsteuer2024.xml should be saved as Lohnsteuer2024Big.xml, otherwise there may be additional problems during the build, e.g. there will be no minified file generated for them. This is a problem with the implementation in compress.js.
2. Potentially rename the topmost node in the xml file such that it ends with Big. For example in the Lohnsteuer2025Big.xml we rename the node from Lohnsteuer2025 to Lohnsteuer2025Big.
3. Run npm run build.
   • Note: If you encounter errors in the .ts files, run npm run build:ts separately, fix the errors in the .ts file and then execute the rest of the build commands (npm run build:declaration && npm run build:native && npm run build:system && npm run build:umd && npm run build:es2015 && npm run build:compress).
4. Add all new files to source control and commit.
5. Update the version. First update in a year increases the major version field to that year (e.g. first new psuedo code for 2024 means that the version would be 2024.0.0), additional pseudo code updates in the same yaar increase the minor version field, patches/bugfixes normally increase the patch version.