We provide the PHP component and payroll tax data, and we monitor each jurisdiction for changes. Our TaxControls component gives you easy access to Federal, State, and Local withholding tax information, all available programmatically.

You can try it out yourself:

  1. File size is around 3567K.
  2. Download the package, then unzip the archive into a directory under the document root of your web server. Point your browser to the index.php file in that directory.