Calculate Portuguese TAX in Google Sheets

2016_table.txt

Echelon	Tax	Overtax
€7,000.00	0.145	0
€20,000.00	0.285	0.01
€40,000.00	0.37	0.0175
€80,000.00	0.45	0.03
€99,999,999,999.00	0.48	0.035

pt_irs.js

/*
* @param double gross_yearly     Gross yearly income.
* @param double net_yearly       Net yearly income.
* @param matrix overtax_echelons Table with overtax echelons. Use table in
*                                PT_IRS but add overtax column.
*
* @return The IRS overtax to the given income.
*/
function PT_IRS_OVERTAX(gross_yearly, net_yearly, overtax_echelons) {
  if (!(overtax_echelons && overtax_echelons.length && overtax_echelons.length > 0)) {
    return 0;
  }
  
  for (var i = 0; i < overtax_echelons[i].length && overtax_echelons[i][0] && gross_yearly > overtax_echelons[i][0]; i++);
  
  var overtax = (net_yearly - 530) * overtax_echelons[i][2];
  
  return overtax; 
}

/**
* @param double gross        Gross yearly income.
* @param matrix tax_echelons The tax echelons to use for tax calculation.
*                            Expects 3 columns:
*                              1. Max echelon amount (eg: €20000 for second ech);
*                              2. Tax for echelon (eg: 0.285);
*  Full table for 2016:
*    €7,000.00	        0.145
*    €20,000.00	        0.285
*    €40,000.00     	0.37
*    €80,000.00	        0.45
*    €99,999,999,999.00	0.48
* @return       IRS tax for given year and tax echelons.
*/
function PT_IRS(gross_yearly, tax_echelons) {
  if (!(tax_echelons && tax_echelons.length && tax_echelons.length > 0)) {
    return 0;
  }
  
  var accounted = 0;
  var tax_total = 0;
  var tax, affected, i = 0;
  
  while (accounted < gross_yearly) {
    if (!(tax_echelons[i] && tax_echelons[i][0] && tax_echelons[i][1])) {
      break;
    }
       
    affected = Math.min(gross_yearly, tax_echelons[i][0]) - accounted;
    tax = affected * tax_echelons[i][1];
    accounted += affected;
    tax_total += tax;
    i += 1;
  }
  
  return tax_total;
}