Tax calculation functions for 2023

taxes2023.R

medicare_tax = function(medi_income, filing_status="joint") {
  addl_floor = switch(filing_status, joint=250000, mfs=125000, single=200000)
  .0145*medi_income + pmax(0, .009*(medi_income-addl_floor))
}

social_security_tax = function(income) .062 * pmin(income, 160200)

tax_with_deductible_brackets = function(income, deductible, bracket_rates, bracket_mins) {
  sum(pmax(0, diff(bracket_rates) * (income - deductible - bracket_mins)))
}

# (assuming standard deduction)
# income: AGI
federal_income_tax = function(income, filing_status="joint") {
  standard_deduction = 27700
  bracket_rates = c(0,    10,    12,    22,     24,     32,      35, 37) / 100
  bracket_mins =  c(0, 22000, 89450, 190750, 364200, 462500, 693750)

  if (filing_status != "joint") {
    standard_deduction = standard_deduction/2
    bracket_mins = bracket_mins/2
    if (filing_status == "single") bracket_mins[which(bracket_rates == .35)] = 578125
  }
  tax_with_deductible_brackets(income, standard_deduction, bracket_rates, bracket_mins)
}

massachusetts_income_tax = function(income, filing_status="joint") {
  standard_deduction = if (filing_status == "joint") 8800 else 4400
  .05 * pmax(0, income - standard_deduction)
}

california_income_tax = function(income, filing_status="joint") {
  standard_deduction = 10726
  bracket_rates = c(0,     1,     2,     4,      6,      8,    9.3,   10.3,    11.3, 12.3) / 100
  bracket_mins =  c(0, 20824, 49368, 77918, 108162, 136700, 698274, 837922, 1396542)

  if (filing_status != "joint") {
    standard_deduction = standard_deduction/2
    bracket_mins = bracket_mins/2
  }
  tax_with_deductible_brackets(income, standard_deduction, bracket_rates, bracket_mins)
}