How to Build a Tax Calculator

const BRACKETS_2024 = {
  single: [
    { min: 0, max: 11600, rate: 0.10 },
    { min: 11600, max: 47150, rate: 0.12 },
    { min: 47150, max: 100525, rate: 0.22 },
    { min: 100525, max: 191950, rate: 0.24 },
    { min: 191950, max: 243725, rate: 0.32 },
    { min: 243725, max: 609350, rate: 0.35 },
    { min: 609350, max: Infinity, rate: 0.37 }
  ],
  marriedFilingJointly: [
    { min: 0, max: 23200, rate: 0.10 },
    { min: 23200, max: 94300, rate: 0.12 },
    { min: 94300, max: 201050, rate: 0.22 },
    { min: 201050, max: 383900, rate: 0.24 },
    { min: 383900, max: 487450, rate: 0.32 },
    { min: 487450, max: 731200, rate: 0.35 },
    { min: 731200, max: Infinity, rate: 0.37 }
  ]
  };

  const STANDARD_DEDUCTION_2024 = {
  single: 14600,
  marriedFilingJointly: 29200,
  headOfHousehold: 21900,
  marriedFilingSeparately: 14600
  };

  function calculateFederalTax(grossIncome, filingStatus, deductions, credits = 0) {
  const standardDeduction = STANDARD_DEDUCTION_2024[filingStatus];
  const deductionAmount = Math.max(deductions, standardDeduction);
  const taxableIncome = Math.max(0, grossIncome - deductionAmount);

  const brackets = BRACKETS_2024[filingStatus] || BRACKETS_2024.single;
  let tax = 0;

  for (const bracket of brackets) {
    if (taxableIncome <= bracket.min) break;
    const taxableInBracket = Math.min(taxableIncome, bracket.max) - bracket.min;
    tax += taxableInBracket * bracket.rate;
  }

  return {
    grossIncome,
    deduction: deductionAmount,
    taxableIncome,
    federalTax: Math.max(0, tax - credits),
    effectiveRate: ((tax - credits) / grossIncome * 100).toFixed(2) + '%',
    marginalRate: brackets.find(b => taxableIncome <= b.max)?.rate || 0.37
  };
  }