tobcalc-lib

A library to calculate the Belgian tax on stock-exchange transactions for foreign brokers and fill in declaration PDF with details. It is the core library used in the tobcalc website.

Table of contents

1. Installation
2. Documentation
   1. Usage
   2. Contributing
3. Example

Installation

The library is published as a package on JSR under @samjmck/tobcalc-lib. It supports Deno, Node and the browser.

Deno

deno add @samjmck/tobcalc-lib

Node (npm)

npx jsr add @samjmck/tobcalc-lib

Bun

bunx jsr add @samjmck/tobcalc-lib

Documentation

If you are using the library, look at the usage documentation.

If you would like to contribute, look at the contributing documentation.

If you would like to test your changes in a frontend environment or elsewhere, look at the frontend testing documentation.

Example

1. Parse the broker transactions from a CSV file using the appropriate adapter.
2. Convert the broker transactions to taxable transactions.
3. Convert the taxable transactions to tax form data that can be filled into a PDF.
4. Fill in the PDF with the tax form data.

// Step 1: Parse the broker transactions from a CSV file using the appropriate adapter
// trading212Csv is a string containing the CSV data from Trading212
const brokerTransactions = await Trading212Adapter(new Blob([trading212Blob]));
// Step 2: Convert broker transactions to taxable transactions using the default securities map
const taxableTransactions = await getTaxableTransactions(brokerTransactions, getDefaultSecuritiesMap);
// Step 3: Convert taxable transactions to tax form data that can be filled into a PDF using the default tax rate
const taxFormData = getTaxFormData(taxableTransactions, getDefaultTaxRate);
// Step 4: Fill in the PDF with the tax form data
const pdfBytes = await fillPdf(fillablePdfBytes, {
	...
	tableATax012Quantity: taxFormData["012"].quantity,
	tableATax035Quantity: taxFormData["035"].quantity,
	tableATax132Quantity: taxFormData["132"].quantity,
	...
});

All necessary functions and variables are exported from the root of the library. A more complete example can be found in examples/example_usage.ts. At the end of the example file, there are examples on how you can write the filled in PDF to a file in different runtimes.