Apps Script para calcular el salario neto en Google Sheets (España)

net_salary.gs

// Based on: https://gist.github.com/straach/30789d4c30fb5174ec52ea7521cc4e4a

// Note: taxpayers without children

// Usage example: =net_salary(18000)

function calculate_tax_by_slice(total, fromCurrency, toCurrency, percentage) {
  if (total < fromCurrency) {
    return 0;
  }

  if (total > toCurrency) {
    let toSubtract = Math.abs(toCurrency - total);
    total = total - toSubtract;
  }

  let taxableAmount = total - fromCurrency;
  let percentageFactor = percentage / 100;
  let taxAmount = taxableAmount * percentageFactor;

  return taxAmount;
}


function calculate_income_tax(value) {
  const taxSlices = [
    { start:      0, end:     12450, rate: 19 },
    { start:  12450, end:     20200, rate: 24 },
    { start:  20200, end:     35200, rate: 30 },
    { start:  35200, end:     60000, rate: 37 },
    { start:  60000, end:    300000, rate: 45 },
    { start: 300000, end: 100000000, rate: 47 },
  ];

  let result = 0;
  for (const slice of taxSlices) {
    result += calculate_tax_by_slice(value, slice.start, slice.end, slice.rate);
  }
  return result;
}


function net_salary(annualIncome) {
  // https://sede.agenciatributaria.gob.es/Sede/ciudadanos-familias-personas-discapacidad/minimo-personal-familiar/minimo-contribuyente.html
  const MINIMO_DEL_CONTRIBUYENTE = 5550;

  let socialSecurity = (6.35 * annualIncome) / 100;
  let relevantIncome = annualIncome - socialSecurity - MINIMO_DEL_CONTRIBUYENTE;
  let irpf = calculate_income_tax(relevantIncome);

  return annualIncome - socialSecurity - irpf;
}