Calculate marginal tax rates using R

Question

I\'m writing a function to calculate tax owed given a level of income according to Australia\'s marginal tax rates.

I\'ve written a simple version of the function that r

Answer 1

I think you're looking for findInterval:

income_tax <- function(income, 
                       brackets = c(0, 18200, 37000, 80000, 180000, 180000),
                       rates = c(0, .19, .325, .37, .45)) {
  bracketInd <- findInterval(income, brackets, all.inside = TRUE)
  plus <- if (bracketInd <= 2) 0 else 
    sum(sapply(bracketInd:3, function(ind) {
      (brackets[ind] - brackets[ind - 1]) * rates[ind - 1] 
    }))
  if (length(plus) == 0) plus <- 0
  tax <- plus + (income - brackets[bracketInd]) * rates[bracketInd]
  return(tax)
}

You just find between each elements your income is, and use that as an index for brackets and the rates. I also added the values as parameters with default values.