Mas info en: http://vampiroz.org/2007/05/calculador-de-irpf.html
*/
if (isset($_GET['sueldo'])) {
$sueldo = $_GET['sueldo'];
$bpc = 1636; # vigente desde ene/2007
$mni = 5*$bpc;
$p_bps = 0.15;
$p_disse = 0.03;
$p_frl = 0.00125; # fondo de reconversion laboral
$deducible = $mni + $sueldo*($p_bps + $p_disse + $p_frl);
$franjas = array(
array( 5*$bpc, 10*$bpc, 0.10),
array( 10*$bpc, 15*$bpc, 0.15),
array( 15*$bpc, 50*$bpc, 0.20),
array( 50*$bpc, 100*$bpc, 0.22),
array(100*$bpc, 999*$bpc, 0.25),
);
$irpf = 0;
foreach ($franjas as $franja) {
if ($franja[0] < $sueldo and $franja[1] > $deducible) {
$gravable = min($sueldo, $franja[1]) - max($deducible, $franja[0]);
$irpf += $gravable * $franja[2];
}
}
echo "Su IRPF es: \$" . number_format($irpf, 0, ',', '.');
exit;
}
?>
Calculo de IRPF
Mas info aqui