Google sheets' App script to calculate income tax according to Indian new tax regime

IndianIncomeTaxCalculations.gs

// Calculate Income tax based on new regime
function incomeAfterNewTaxDeductions(CTC) {
  var initCostToCompany = CTC
  var costToCompany = CTC

  var totalTax = 0.0
  var new_tax_regime = {
    1500000: 0.30,
    1250000: 0.25,
    1000000: 0.20,
     750000: 0.15,
     500000: 0.10,
     250000: 0.05
  }

  // Get the keys; Note that the keys are in string format
  var slabs = Object.keys(new_tax_regime)

  // Sort the keys
  slabs.sort(sortDescendingOrder)

  for (var i = 0; i < slabs.length; i++) {
    var upperTaxSlab = parseFloat(slabs[i])

    if (costToCompany > upperTaxSlab) {
      var currTax = parseFloat(new_tax_regime[upperTaxSlab]) * (costToCompany - upperTaxSlab)
      totalTax = totalTax + currTax
      costToCompany = upperTaxSlab
    }
  }

  var healthEducationCess = 0.04 * totalTax
  totalTax = totalTax + healthEducationCess

  var incomeAfterTax = initCostToCompany - totalTax
  // Logger.log("CTC: " + initCostToCompany + " Tax deducted income: " + incomeAfterTax)
  return incomeAfterTax
}


function sortDescendingOrder(val1, val2) {
  // Converting string to int
  ele1 = parseInt(val1)
  ele2 = parseInt(val2)
  if (ele1 > ele2) {
    return -1
  }

  if (ele1 < ele2) {
    return 1
  }

  return 0
}

How to write custom functions and use them in google sheets: link