Federal Income Tax Calculator Formula

Understand the math behind the federal income tax calculator. Each variable explained with a worked example.

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Formulas Used

Federal Tax

federal_tax = taxable_income <= 11600 * bracket_adj ? taxable_income * 0.10 : (taxable_income <= 47150 * bracket_adj ? 1160 * bracket_adj + (taxable_income - 11600 * bracket_adj) * 0.12 : (taxable_income <= 100525 * bracket_adj ? 5426 * bracket_adj + (taxable_income - 47150 * bracket_adj) * 0.22 : 17168.5 * bracket_adj + (taxable_income - 100525 * bracket_adj) * 0.24))

Effective Tax Rate

effective_rate = taxable_income > 0 ? (taxable_income <= 11600 * bracket_adj ? taxable_income * 0.10 : (taxable_income <= 47150 * bracket_adj ? 1160 * bracket_adj + (taxable_income - 11600 * bracket_adj) * 0.12 : (taxable_income <= 100525 * bracket_adj ? 5426 * bracket_adj + (taxable_income - 47150 * bracket_adj) * 0.22 : 17168.5 * bracket_adj + (taxable_income - 100525 * bracket_adj) * 0.24))) / taxable_income * 100 : 0

Variables

VariableDescriptionDefault
taxable_incomeTaxable Income(USD)75000
filing_statusFiling Status1
bracket_adjDerived value= filing_status == 2 ? 2 : 1calculated

How It Works

2024 Federal Income Tax Brackets (Single)

| Taxable Income | Rate | |---|---| | $0-$11,600 | 10% | | $11,601-$47,150 | 12% | | $47,151-$100,525 | 22% | | $100,526-$191,950 | 24% |

Married Filing Jointly brackets are roughly double.

Worked Example

Single filer with $75,000 taxable income.

taxable_income = 75000filing_status = 1
  1. 0110% on first $11,600 = $1,160
  2. 0212% on $11,601-$47,150 = $4,266
  3. 0322% on $47,151-$75,000 = $6,127
  4. 04Total = $11,553, Effective rate = 15.4%

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