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Open the calculator. It runs taxsim-py in the page through Pyodide, in a web worker. Nothing is sent to a server. (The link works on the published site; locally, build it as shown below.)

  • One household: a form grouped like TAXSIM's, with marginal rates, detailed worksheets and calculation mode as options.
  • Upload a file: a CSV with one household per row (needs state, mstat and year, or set the year on the page), a preview of the results and a CSV download. The calculation runs in a web worker, so the page stays responsive, but very large files still need browser memory; use the command line for those.

Run it

uv run python scripts/build_web.py      # builds the wheel into web/
python -m http.server -d web            # then open http://localhost:8000

It must be served over http, not opened as a file. The documentation site includes the calculator at calculator/. Build the whole site, with preview, using uv run --no-project --with mkdocs --with mkdocs-material python scripts/build_docs.py and then python -m http.server -d site. Add --deploy to publish it to the gh-pages branch (GitHub Pages must be set to deploy from that branch).

Use it from your own page

import { loadPyodide } from "https://cdn.jsdelivr.net/pyodide/v314.0.7/full/pyodide.mjs";

const py = await loadPyodide();
await py.loadPackage(["polars", "pyyaml", "micropip"]);
await py.pyimport("micropip").install("emfs:/tmp/taxsim_py-0.1.0-py3-none-any.whl");  // after writing the wheel to py.FS

const calculate = py.runPython("import taxsim_py; taxsim_py.calculate_row");
const result = calculate(py.toPy({ year: 2023, state: 5, mstat: 2, pwages: 80000 }))
  .toJs({ dict_converter: Object.fromEntries });

calculate_row takes and returns plain dicts, so values cross the JavaScript boundary without conversion code. Pass keyword options such as mtr or idtl from Python.