var personal, A1, A2, A3, B1, B2, B3; function calculate(year,income,tax){if(year=='0'){window.alert; document.all.zwrot.value = '';} 
else{if(income==''){window.alert;document.all.zwrot.value = '';}
else{if(tax==''){window.alert;document.all.zwrot.value = '';}
else{switch(eval(year)){case 2006:personal = 4895; A1 = 2090;A2 = 30310;A3 = 0;B1 = 0.1;B2 = 0.22;B3 = 0.4;break; case 2005:personal = 4745;A1 = 2020;A2 = 29380;A3 = 0;B1 = 0.1;B2 = 0.22;B3 = 0.4;break;
case 2004:personal = 4615;A1 = 1960;A2 = 28540;A3 = 0;B1 = 0.1;B2 = 0.22;B3 = 0.4;break;case 2003:personal = 4615;A1 = 1920;A2 = 27980;A3 = 0;B1 = 0.1;B2 = 0.22;B3 = 0.4;break;case 2002:personal = 4535;A1 = 1880;A2 = 27520;A3 = 0;B1 = 0.1;B2 = 0.22;B3 = 0.4;break;}zwrot(income,tax);}}}}
function zwrot(income,tax){var inctax, res1, res2, res3, lev1, lev2, lev3, taxdue;inctax = Math.max((income - personal), 0);res1 = Math.min(inctax, A1);lev1 = res1 * B1;res2 = Math.min((inctax - res1), A2);lev2 = res2 * B2;res3 = Math.max((inctax - res2 - res1), A3);lev3 = res3 * B3;taxdue = lev1 + lev2 + lev3;document.all.zwrot.value = Math.round(tax - taxdue);}